Gas Recirculation Valve (egr Valve) problems of the 2001 Toyota Avalon

I have an oil engine sludge problem that Toyota is trying to place the cause on my shoulders. My husband performed oil changes at regular intervals at about 4500 miles between each change. Twice we have had other change the oil. Once the dealership and once a texaco express lube, both which we were able to obtain receipts for. The problem began when we did not save the receipts from our oil and filter purchases. Any and all work done on the car was entered into our maintanance manual. A few years back we received a letter from Toyota explaining the sludge problem and what they would do if it occurred. Evidently what they said isn't worth the paper it was written on. They want me to pay $750 to the dealership before they will do any work on the car. $250 is for incidential work that might have to be done in relation to the sludge problem and the other $500 is a deductable. Excuse me but no where in the letter or my warranty and ownership manuals does it state that if we perform the work we are required to keep our receipts. I spoke with the service manager at the dealership, who tried to refuse to give me the name of the district manager, and did refuse to give me a phone number that I could reach him at. He said our log of the work wasn't good enough for the Toyota corp. , and that people had been known to falsify records. I have never had my integrity questioned before but now because of Toyota's building of an engine prone to this type of failure all the sudden I've become a liar.