I bought a Vauxhall Tigra last year and have just sold it now to buy a mini. The dealer I bought it from has said because the service book wasn't stamped the they wanted another £400 from me but will refund it if I can prove it. I have spoken to both Vauxhall and the place I bought the car from and they both say the do not keep records of this. Is there any other way I can find this out?