Hmm, some ideas.

You need a document from your mechanic, detailing what he found, how he
fixed it and remedial action needed into the future.
AND what his qualifications, and experience level actually is.
You'll need a document yourself detailing time expenditure and
inconvenience matters - and that sounds significant already.
Both need to be signed in the presence of a JP or what ever passes for
that in your part of the world.
A Stat Dec will do the trick, but better to try for an affidavit -
they're specially for Courts to play with.
You'll need to detail the initial refusal, the talk of 'meetings' which
the baddies may get to prove actually (didn't) happen. ie, set them up to
force them to lie to the tribunal, and hope like hell they'll trip
themselves up. With any luck, they'll send a junior shyster to the case,
and they may well cock it up if your groundwork can force them to prove
stuff happened which probably didn't, or at least that they can't prove
did.

Then.
Tell the mobil mob what you've got, and ask if anyone else has had
problems with fuel from the outlet you copped the swill from, because
you'd of course like to compare notes because you figure you'd hate to be
mistaken in thinking you were the only one with a problem... Only
reasonable.
Make damm sure they are convinced you are going to seek that out whether
they tell you anything or not - if necessary by paying for a public
notice in the biggest selling newspaper in the area.This *should* get the
OilCo's full attention - because they know that others that have not had
a shot at them on the matter will be following you when you do - IF the
others have you as a leader.
For all you know, there may be others involved already - the OilCo will
NOT tell you that. in which case, you're a follower - but nonetheless no
less dangerous to their bullshit good name. But hopefully small claims
cases will tell the story.
Do not, yet, mention so-called current affairs shows. The 'sensational'
value for them is where small claims supports Big Business against the
little man on a slow news day, of course. That value has to exceed the
value of the advertising placed by the villain of the piece. If you do
later go that way, check the TV for a while and figure out which station
gets less revenue from the baddies. That'll be the one to seek help
from;-)
Tell the OilCo people this is their last chance before the whole shootin
match is sent off to small claims.

And just then do it. No matter what they say.
Fast.
Small Claims are egotistical enough to believe they can only solve claims
that the consumer has tried quite hard with first. They'll want evidence
of that. It's their Face, you see.
Do NOT wait from any OilCo bullshit referrals to head office or whatever
they try on - because justice delayed...etc.
Besides, it's a fight - whether you think so or not. Ferinstance, ever
seen a boxer give their opponent a few minutes to recover during a round?

Anyhow, then you sit back and wait for a result.

Remember to record everything that happens, including the time you spend
on the matter. Every second. It will be needed later, because you're
going to ask for consideration of that.
if the car needs attention during this period, get it documented and make
sure you commmunicate that in writing to both the OilCo and the claims
mob. The bill/claim is growing as time goes on, you see.

That initial denial is the key. Dead standard procedure, I'd say.
The idea is to throw you off the trail by making you think you're the
only one who got bad fuel, because they initially won't entertain the
possibility that it happened at all. So you were being worked over,
there.Natch;-)

Oh, and then there's the recent wet weather/flooding in that area?
Not a bad out to use for the baddies - but they shouldn't get that
opportunity until things get really down and dirty. IOW, don't venture
that at all - it's 'their' out that avoids considerations of shite
business practice, and they're more likely to volunteer to pay out if
think their face is intact.

Might as well properly intimidate the opposition:
Get an inspector to go check the fuel at the outlet as soon as you can
manage it. Hope like hell your muddied up fuel filter is available as
evidence. Was the mechanic smart enough to put some of the goop from your
fuel tank in a jam jar? Can the inspector have some of that if he asks?

HTH

One last thing. Corporations think nothing of spending shitloads of money
on matters like this. Make sure round 1 is the one they're stopped on. Go
for their balls from the outset. A bit like contesting speeding fines -
you simply have to smash them up in the free court.
After that it all starts to cost you money you don't have, because YOU
don't have institutional shareholders who don't give a rats arse about
the morals of any given situation.

Wouldn't it be a good thing if they simply paid up right now happening on
the face-saving rain thing as their get-out clause:-)
__

Toby

Hey Cyborg is it true they've started introducing unleaded petrol into
Tasmania?

Pity it isn't likely to work for me... mainly because the outlets for
both of those get their stock from the same bulk terminal where I am.
Same stuff, only a different truck delivers it!

Similar reciprocal arrangements between the various oil companies
apply in most parts of Australia.  Dunno specifically about Perth, but
I'd be surprised if most of your fuel wasn't the stuff that comes from
Kwinana.

Of course the hygiene that's likely to apply to the individual
underground storage facilities at the outlets for the various brands
is something else again.  :)

Seems customer service is a thing of the past.
Many years ago when I was a courier I used to fill up my van everyday at
the same servo, the owner approached me and asked if I had had a problem
with my LPG convertor, I said I had but I had fixed it myself the
previous day.
He said he must have had a bad batch of gas and offered to pay for any
repairs, I wouldn't expect too many servo operators would be as honest
these days which is a very sad thing.

Daryl