Gas tank implosion on 300E, twice???
 

I have an 87 300E and the gas tank imploded. Had a new one put in and a week later the same thing happened. I asked some experts (besides the ones who worked on the car) what would cause this and they said clogged vacuum valve? Anyway I asked the guy who worked on the car if he checked those and he said yes and he says there is a short in the cluster in dashboard and that caused the tank to implode. It seems farfetched to me. Is anything like a short able to cause this to happen? I think the mechanic is covering his own butt because he never checked in the first place. Please help me with this because I want to show negligence on his part to save cost of 2nd tank and installation which he chaged me for again.