left brake light out only

everything is functioning except the left brake light. checked bulbs. signals ok. took to garage and they said i needed a new signal switch. when i left, no signals working. took back and (although not admitted by mechanic) button for hazard was also broken off. said dust etc. could get in hazard so he messed around with it and all was working, so i told him just to glue it back on. the signals once again are working so i was back to square one. but mechanic said signal switch will eventually go and have to be replaced.
1. is what he told me about the signal switch valid?
2. i had assumed when i brought it in, there was just a broken wire or bad socket since it was only the brake light on the left side - should the mechanic have looked at that first? i was told after he checked the bulb he went to the signal switch.
thanks so much for all your help!

Mine light brake light wasn't working either.Had turn signal switch replaced. Now no problem hope this helps.

I wouldn't doubt the signal switch at all. They're junk, and they go bad constantly. Replace it - even if you're not sure, because eventually, it will go bad anyway.