Popping out of Reverse

Got a new clutch fitted on my 03 TD4 about 3k miles ago.

When reversing, I select Reverse ( obviously), but when moving backwards; the gear occassionally disengages.

Any thoughts?

If your lucky it might be something disturbed on the gearstick linkage when the clutch job was done making it not fully select reverse at the box. Would hate to think you've got some gearbox trouble itself looming.
Don't know about the manual Td4 as mines an auto but I'm sure someone in the know will be along soon.

This problem is getting worse - now takes me ages to select reverse. Had it back at the garage that fitted the clutch, but they couldn't find the cause. It sits in reverse when the engine isn't running ( not much use).

Any thoughts? Am I looking at gearbox problems? Everything else is fine - apart from reverse.

If it didn't do it before the new clutch went in then I'd be a bit more insistent with the garage who did the repair. As it's getting worse something could be about to drop off and you'll lose all gears. Sounds like a selector problem. I believe yours will have a series of little ball joints that need pressed together again on reassembly, maybe one isn't right in or snagging somehow. It could even be something as silly as something caught down below the gaiter inside the car stopping the lever come right across. Have a look down there for a dropped spanner or something! It's been known.