Replacing the ECU

Has anyone hear had to replace the ECU on their Octavia? If so what were the problems before hand and was the problem fixed?

The engine management light on my y-reg keeps flashing on (with no noticable change in peformance) and the dealer wants to chane the ECU. I really don't think thats the ECU is the problem :confused: , but it would useful to hear any similar tales where the ECU was changed, also how much it cost you if it comes to that :eek: .

Regards