Isn't the SRS the "Supplemetary Restraint System", related to the
airbags?

That does not seem remotely connected to the alternator. It is hard to
believe that you were able to drive the car normally for a week with a
bad alternator.
Unless your alternator broke on the way to the dealership, there's a
good chance it was just fine.

To prove this will be hard:
They most likely plugged a scan tool into your car. They noticed that
it had a code related to an electrical problem. That code might have
been set in the course of its life due to, for instance, a bad battery
connection or just a glitch.

An error code is really just an indicator: Sometimes error codes are
symptoms and sometimes they mean nothing.
I suspect they noticed the code, cross referenced it to a likely cause
(alternator). Using a flow chart is not a substitute for using one's
brain, but it is in their interest to (1) get your car fixed soon and
(2) charge you as much as they can.
They swapped the alternator, reset the codes (including the code that
turned your SRS light on) and everything is fine now. Of course, a
reset of the code may have done the same thing -- impossible to say.

Hate to say this but, unless you had a voltmeter on the alternator and
know it was putting out 14.5 volts while the car is running, you could
complain but I doubt they'll listen to you.

Remco