A4 2.5 tdi quattro sport tiptronic problem

Hi all ,am new to this forum and have spent ages going through previous threads regarding my problem to no avail,my radiator developed an internal leak between the gearbox cooler and the rad and consequently all atf went into the cooiling system,have now fitted new rad ,but on topping up the gearbox following the guides the box now slips in first an reverse kicks down into first with a bang,I then renewed the filter in the box and tried again if anything its a bit worse,it doesnt do it all the time ,but pretty much most of the time its revving its bits off to pull away,Hooked up to the computer were a couple of codes initially which prob due to emptying the box ,rest them went for a weeks worth of driving ,no codes in box at all now but still slipping like a good un,can anyone help or know of good autobox specialist up North lincolnshire yorkshire way
Cheers Matt:zx11: