Your complaint definately speaks to the quality of the personal, not to the
products they sell.  If you want to hear horror stories about quality of
work and have a half a day I'll tell you all about my experiences at one of
the best known Olds dealerships in Winnipeg from when my Aurora was still on
Warranty.  The heater hose clamp they left loose was the least of the
problems I had with them.  How about when they R & R'd the trans and didn't
put the wiring harness back in place properly and cooked it against the
exhaust manifold.  Or the time they had the console apart and to replace the
cigar lighter, put it back together with the wiring harness for the light in
the shifter atached at the wrong points resulting in the breaking the light
off the shifter after it stretched the harness when it was put into Park
($1400 for a new console.) Or the time they replaced the speedo and broke
the clips on the dash bezel and put it back with tape($200). One of my
favorintes was the time after the car was off warranty and the bearing on
the ac clutch packed up.  The car had about 90,000km and they wanted to sell
me a new compressor ($1900). For some reason they had discharged the system
as well by the time they called me.  I told them to put it back together and
leave it alone. I took it to another mechanic I know and had him replace
just the bearing ($200). It's still working fine today at over 200,000km.
I've got a list longer than your arms of some of the most incredibly stupid
moves i've seen.

There's no assurance of quality workmanship anywhere, regardless of the name
over the door.  Find a good reputable mechanic and stay with him and pay him
what he's worth, regardless of whether he works for Canadian Tire, the
dealer or anyone else.
As to Canadian tire parts, most are brand name (Certified Brake Parts, Noog,
TRW, Fenco etc, the same as you'd get from any jobber.  Some are re-branded
in CTC's name because of the volume they sell. Many auto shops used to run
down their products because CTC was retailing to the public at the prices
the dealers were buying for.  Years ago they sold the lesser quality name
brands (your econo muffler or brakes), but now all of the jobbers offer the
economy quality as well as the premium quality and Canadian Tire offers the
premium as well as the lesser.  Almost every manufacturer markets 2 or more
levels of product these days.
BTW, I'm a licensed mechanic that worked in the trade for 15 years, but have
been out of it for 17, so I have some idea of what I speak.