Owners/service Manual problems of the 2008 Toyota Tundra

My vehicle now has a little less than 70,000 miles on it, and has a feature which automatically locks the doors at 15 mph, then unlocks them when the transmission is put in park. However, the doors will no longer lock unless I do so manually with each door; the power mechanism has failed. The dealer claims that the central relay and controller of the power lock system is ok; but the power lock actuator (small motor) on each door has failed individually. I find it almost impossible to believe that each one of these parts has failed in the same vehicle relatively early in the life of the vehicle unless there is either a faulty design or extremely poor quality of the parts involved. In either case, the manufacturer should be responsible for the cost of the repair, which the dealer estimates at $1,746. 00! please help me with this if you are able to put some pressure on Toyota. I would appreciate it.