Warranty Paperwork (proof of works)

I have recently purchased a 59 plate VW golf estate from a main VW dealer. It came with the statutory 3 months warranty.
In the first week I took it back complaining of a noise in the clutch. The dealer took it back and afterwards said they had replaced the clutch.
They had the car a suspiciously short amount of time and the clutch seemed no different.
When I asked them for the paperwork detailing the work they had carried out, the salesman said they couldn't provide it as their system would not let them print from it. Claiming that all the work that had been done is stored electronically on their system.
When I come to sell the car again I would like proof that the work had been done.

Am I entitled to paperwork for work done under warranty and if so can I demand it? Where do I stand?

Any advice welcome

Thanks in advance.

Ian