A very common fault of those pumps is too over heat and it actually fries the harness at the pump. have them do a thorough check of the electrical connector at the pump and also do an amp draw test of the new fuel pump. If the new fuel pump draws 9.0 amps or more, you may have wiring problem. They shouldn't charge you more than half an hour to check the draw. Also put in a new relay.
Fuel pump issues are very common on those vehicles, but the later pumps are much better than the originals. There's no good reason to be back in there four times in one year........