The TIPM unit is a known issue. Oftentimes, the connectors, which have a large number of small connection pins, are where the failure comes from. The pins will corrode or break causing an intermittent issue. So, what they are telling you is likely correct, especially with the number of miles on the vehicle.
What I suggest is this: Replace it yourself. Chances are you can find a new or remanufactured one online for under $500.00. They really aren't that difficult to replace. Once you disconnect the battery, it is a matter of unbolting the unit, disconnecting all the connectors, and then reinstalling everything.
If you look at the pics below, I included the directions for the removal and replacement of the TIPM on this vehicle. Take a look through them to see if you are comfortable doing the job. I will be here to help if you run into trouble.
Let me know.
See pics below.
Images (Click to enlarge)
Tuesday, August 31st, 2021 AT 9:13 PM