Gearbox issue help please

Hi every one new yo this stuff I was a massive MG freak and owned a lot of them and when my last one was written off at Xmas I bought my self a s type 2.7d xs pef code. I’m in love with it the best car I’ve ever owned yet i say that till two weeks ago and the auto box started play up. It slams it self in gear at time and some time it feels like it slips and the car ends up reving high and going no where fast. So I went to my garage and he said that a gearbox service with new pan as filters built it should sort this issue but with a very said look on my face I tell you all that it hasn’t at all if any thing and I think it may be get more often its happening. I’m looking at gaining some ideas of what it maybe as I’m new to autos too ive been told it could be solenoids in the gear box so could some one please help me get to the bottom of it thanks in advance

Welcome, Danny!

It would be helpful to identify your country of residence, so that appropriate help can be extended to you.

Well I am so so sorry didn’t even think about that at all. Forgot I signed up to this page as I have heard nothing at all. Thank you Paul for your reply i don’t know how to add it to my main question but I can write it here so here goes

I live in the south west of England :uk: a place called Plymouth i really do hopes this helps as I really do need it as cr dropped its water yesterday aswell but checked i can do that so off to do that once shop open so can buy the parts

For the transmission problem, try Bristol Transmissions. They have been featured in the JEC magazine and advertise in it regularly.

What model year is the car? Earlier cars have the Ford 5R55N trans and later cars have a ZF 6HP26 trans.
Changing the fluid and filter was a good idea; it worked with mine.
One possibility is it needs an adjustment in the shifter cable, which is located in the console.
J gate shifter 011
There is also a white plastic part in the J-gate shifter that is prone to wear, which can mean you fail to get it in the right gear, i.e. sometimes in neutral when you think you are in drive, and there is an aluminum replacement part on the market for it.
J gate shifter 004
J gate shifter 006