I wouldn't blame you, especially if their customer service isn't up to snuff. FWIW, you could call Canon and explain to them that you are having issues with TTL flash on your A2. If they suggest that you use a Canon flash that supports A-TTL, insist that you prefer regular TTL flash metering. It would be interesting if you had access to a 420EX or 550EX to see if it locks up the camera as well. They should default to TTL metering if used on a type-B EOS body (i.e. A2, A2e, EOS 5).
None of the third parties, with the exception of Metz I think, license Canon's code for their flash metering/communication. The systems are reverse engineered and prone to error. Did you try to remove the batteries from the camera for a few minutes to see if that helped? I'm using a Sigma 500 DG Super for on-camera flash these days. However, since it has no external power options and will not work with Pocket Wizards, it will always stay on-camera. It recycles pretty decent with a set of 2050 mAh NiMH Duracells. Never had a chance to use it on a film body though.