2009 C30. Gearbox issue

[Tiny Tim 077]

Hello all

We have an issue with C30 powershift. The car only has 85 000km and once the car heats up on a long drive/motorway it start shifting up and down through the gears. It is just bizarre as the milage is low and the car has been kept spotless and fully maintained. Just come out of motor plan and Volvo is saying They can't seem to find the problem and it is R60k for a new box.

I a sure this is a electronic or upgrade issue and not the box packing up.

Any ideas?

Thank you