If there would be a engraving malfunction, there should be an error message (P code).
And the car should run into a fail-safe programm which does only allow 2 gear and reverse.
But obviously this doesn't happen. So we don't get an error message.

If the transmission get's much too hot there can be 3 problems
- cooling circuit doesn't work correct
- oil filter is plagued
- much too low ATF oil level

Did you do any modifications at your car?
Like sprint booster, modifications at the stereo amp, centre console ... ?

If you let change the ATF oil, make shure that they do a complete spileage. To do that, they will need a vaccum pump and much more than 5 litres (5,28 quarts) of atf oil for a standard atf oil exchange. i think they will need minimum 8 (8,54) to 12 (12,68) litres (quarts). And make shure they'll install a new oil filter and level the atf-oil level exactly. There are diagramms in the Crossfire service manual, that show how high the oil in level in dependance to the oil temperature should be.

Manuals:
https://www.crossfireforum.org/forum...ollection.html