A4 1.9tdi 2000 auto gearbox problem????

Hi guys I'm in need of some serious :1zhelp:, I've had this car 5 yrs and its been my pride and joy. The other day I was driving it and it felt like it lost lots of power. I couldn't get the thing to rev over 3K rpm. I then decided it was time for a service and took it to a family friend that fixes all my cars and is an ex bmw garage worker. He doesn't know whats wrong with it and we've given the car a full service, all oils and fluids have been changed along with filters including gearbox oil filter.
Does anyone know whats wrong? It seems like the gearbox is in a safety mode. Helpful info will be much appriciated. Thanks :biglaugh:

Taylon