On April 15 I took my GMC Sierra 1500 to the dealer just south of Denton, I requested they perform the 30,000 mile service, first they wanted to do 'their' recommended service at a cost of 400-500 dollars. I said, "no way it runs good leave the fuel injectors alone, just do whats in the owners manual." Instead of checking and adding as required they drained and replaced the rear end lube, they drained out synthetic gear lube and filled with new at a cost of 27 dollars a quart x2. Total cost for the rear end service was 141.64 including 10 dollars to throw away my good gear lube. When I picked up my truck I questioned the charge for locking rear end service as my truck doesn't has a locking rearend, and was told by the service writer that all GMC's have locking rear ends. I realized then I was talking to someone willing to lie to clear a service ticket. I paid the bill, got my truck out of hock and out of their hands. When the customer followup arrived I unloaded, over the next few weeks I talked to many people and the final call was from the operations manager, He was pleasant and agreed with me that a wrong had been committed, he agreed to refund the charge for the rear end service. Today I received the check for 141.64 dollars.