details for Maurice Stones (REME)

Hi there, I'm trying to find the British Army record of my father, Maurice Stones, who was in the REME during WW2. I have tried the "normal" line of tracing, via MOD.gov.uk, but they haven't cashed my cheques (twice), so I can only think there is some problem in communications.....I have his birth certificate and his death certificate, but not his service number....any help would be much appreciated...Thank you