Tire Tread/belt problems of the 2002 Audi A6

Purchased new cooper tires from graham automotive @801 west 41st st, sioux falls, sd 57105 on may 10th of 2004. My Audi had 24,105 miles on it when I picked it up. On Nov. 17th, 2004 I was returning from sioux falls, sd @ about 11pm and I had a blowout on the drivers front. It had 10,753 miles on it. I had to call several times to get them to give me 75. 00 on the tire I had to get. Well on may 23rd, 2005 I had ron loban from dale's alignment of brookings, sd look at my tires. The 3 were so wore out he recommened that I not drive the car. I drove it to my residence which about 8 miles from my office. On the way to work I was about a mile from work and I blew the drivers side front tire out again. The tires are at dale's alinment @1006 main Ave s. Brookings, sd 57006- phone # for them is 605-692-5712. Graham automotive said they can't help. I feel that with the mileage of 40805 when the second blow out occured. That means I had 16,700 miles on 3 of them and they were shot and the 4th blew with only 10,755 on it there had to be something wrong with them. Please help in getting some help for this. I thank you. Ila k. Swenning.