Automatic Transmission Control Module problems of the 2003 Lexus ES300

Since my acquisiton of a 2003 Lexus ES-300, the vehicle has displayed very uneven shifting and hestitation as the transmission upshifts and downshifts, particularly at low speeds. In response to my complaint after 2,000 miles of driving, the dealer examined the problem and I was told that Lexus had provided a solution in the forms of a "re-flash" for the on-board computer. This was performed, however, failed to improve the situation at all. When I complained a second time after 5,600 miles of operation, the dealer told me that nothing further could be done and referred me to the Lexus national customer satisfaction line. After several calls I was told by a national representative that the vehicle was operating as designed and nothing could/would be done. In its present condition, the vehicle is both unpleasant to drive and unsafe since it hesitates before accelerating.