What sort of money are you looking to spend on a replacement?
I'd look at:
polo 1.9 tdi sports - 100bhp quite quick, 50+ mpg and cheap tax. Circa £2500 - £4000
Ibiza sport/fr 1.9 tdi - 130 bhp as above really - £2000 - £5000
Fabia VRS 1.9 tdi - 130 bhp " " £3000 onwards
Diesels arent everyone's cup of tea but for the money, you're getting a nippy, cheap to run little car with any of the above