Just after some ideas because im all out of them. Around 5 months ago I was out in my 16v and I noticed my clutch started to slip. So without further ado I removed the gearbox and fitted a new clutch kit (very hard job on these 8 hours plus). But strangely my clutch wasn't worn out. After rebuilding soon road test still clutch slipping So I fitted a genuine Citroen clutch cable but still slipping. So out came the gear box again Checked for contamination oil ECT but dry as a bone. Removed clutch. I fitted a new flywheel and changed clutch for genuine one.I noticed the clutch release arm had play and I had another good gearbox so I fitted that Sewell to iliminate any problems. So I've fitted new clutch, flywheel, cable, changed gearbox. Road test all good great until slipping again what am I missing any advise would be g

Are you really sure, you have installed and adjusted the cable correctly? You first mentioned a clutch kit which you replace by an original clutch, this is also a kit(including new pressure plate)?

Yes cable has been checked and checked again and I've tried adjusting cable to all different positions still the same

And a full clutch kit was fitted

Can you confirm that the clutch release arm fully engages the pressure plate? Could it be that the pin that secures the clutch arm is preventing it to fully engage?

I have cleaned and made sure clutch arm moves freely and pin is correctly located. It is a pull type clutch so folk hooks behind release bearing. I'm out of ideas

If you mounted everything correct, the crankseal is not leaking oil on the clutch than the flywheel you fitted is not the correct one or has been severly skimmed.

If the components are the correct ones than it must be a fitment issue.

I do not know if it is possible to mount the box in the following options:
Are you sure you did not fitted a PUSH type clutch fork?
The clutchbearing also has a top and bottom indicator, maybe you made a mistake there.

Very hard to judge on the other end of a computer screen.