So, why not go into the shop, ask for a supervisor/man in charge/boss/whoever....ask nicely when your problem will be dealt with, and if fobbed off with excuses again, then create merry hell in the shop...describe in a very loud voice (so everyone in the shop can hear) what's happening (or what's NOT happening) threaten to call the local newspaper and refuse to leave the shop until you have either a new esc(s) in your hand or have something in writing, and witnessed by another customer, that says that the shop is doing something about the issue. Threaten to call the local radio station as well, and start mentioning such things as legal representation, etc. In general...make a complete nuisance of yourself in the shop and make sure that other customers in the shop know why.
Oh...and take a camera and a pocket voice recorder and make a great show of recording everything that's said to you and take photographs (with the flash on)....make your point loudly and make sure everybody hears it. And have a notebook handy and write lots of stuff in it...especially names.