Basically what happened is that about a week after the clutch parts were changed, I had a bad gearbox leak while driving at speed. It went back to the garage and they said it was the N/S inner cv boot hadn't sealed correctly so they replaced it as a gesture of goodwill.
I then used the van around town for a couple of weeks and when I next did a higher speed run with it, I had the exact same problem.
The van went back to them and they had it for two days saying they couldn't find a fault, then on removing the gearbox, have told me the gear selector shaft is worn and this is the problem.
I know a little about mechanics and questioned this diagnosis. I then researched the internet and found that the van is only supposed to hold 2.7 litres of fluid, the garage has admitted filling the gearbox to the filler hole, which I believe is incorrect for this van?
I've also researched and found that the van will basically try and shed the oil out of anywhere it can when under load as it is overfilled. Is this correct?
I've asked on here as you are a Renault expert and this could potentially become a legal matter if they have damaged my gearbox.