Automatic gearbox issues

Hi everyone wonder if you can help. My freelander (y reg) started with a problem changing from second to third the best way to describe it is almost as if the clutch is slipping it would bounce up the rev limiter and if I eased off it went back down and changed gear. The 'bouncing' became more frequent the further I travelled. I kept it close to home and took it to a garage for a gear box oil change, I was told my oil was fine they did nothing further to the car (husband was there) and on we went. The next time out it started flashing F and thinks it has decent mode on....to me I'm wondering if its a sensor seeing as really all they can have done is knocked something but maybe not.....any ideas welcomed?

Search out hippos thread about f4, also oil change is good, biggest problem is finding someone to do it properly!

Hopefully yer got it sorted by now. F4 flashing could be the barrel connectors loose or a wiring harness fault. Search me posts for the resistance checks. Ere's a video on how to do it:

Freelander 1 v6 Jatco Auto Gearbox - Measuring the Solenoid and Sensor Resistances