Hi im assuming it,s a 4 speed?
Have you got any lights flashing on the dash when it wont change gear properly?
When it wont change gear properly is it when the car is cold first started in the morning or after a run when it,s hot?
When it plays up put the gear lever back to manual 1 then change up to 2 then 3 then 4th see if it will work ok this way.
Does it pick up reverse ok?
The garage that looked at it did they plug in a diagnostic tool to see if there was any codes stored?
Let me know as much info as possable and i,ll do my best to help you.
Just to let you know im not just guessing ive been rebuilding gearbox,s for over 15 years now.
Richard
rbtrans@btinternet.com
Richard
August 2007