My 5 speed was in need of some TLC by around 140k, hard, jerky shifts etc. Fluid change helped a bit but having the valve body changed by a local Volvo specialist restored the shift quality pretty much back to new.
Unfortunately a few thousand miles later it started slipping when cold and although it was fine generally eventually had it rebuilt by these guys for around £3k.
Crucial Automatics.
Any good auto gearbox specialistic should be able to do the job though.