My mate recommended one of the OBD2 code readers for Seat/VW/Audi/Skoda off eBay a while a go and for £15 inc. P&P thought it was worth a try! Search for OBD2 Seat and it is one of the orange ones - they look cheap, but it has worked well for me.
Had one for a few weeks now and works perfectly, used it on Saturday and brought up 3 codes (numbers only, no text etc.), the manual supplied gives the code numbers and the fault that it means. The codes I needed weren't in the manual but were in the code section on this forum so had no troubles!
Although I didn't realise you could get a vagcom cable for so little.