Tank Assembly problems of the 2002 Audi Quattro

The Audi cars have a problem with the gas tanks which could lead to explosions. My 2002 Audi has about 100k on it, which is when I started smelling gas. I took it into the dealer in 2008 for a recall, and at that time they serviced a part of the fuel system, for which now there is a recall. Then this year, smelling gas, I had the rings changed, but now smelling gas again, my Audi mechanic says the tank is not repairable. He pulled it as far down as possible and used a scope on it to see if it could be repaired. Now I am looking at about 2k in bills for a new gas tank. I called Audi and asked their advocate about this, asking about if it was related to the recall, and of course he said no, that with high mileage cars gas tanks can give problems. I know of many Audis who have had to replace gas tanks; this is not normal. Audi needs to be investigated for this. I have found many other instances just by googling this problem on the web, and my mechanic, who only works on Audis, has replaced several tanks. He used to be an authorized parts center for Audi so he knows that they are aware of the problem.