Took my 03 E320CDI into Mercedes Sunderland as battery light on. After reading many threads on this forum seemed regulator pack might be broken. Seems most dealers will try to replace Alternator (£1500) however I was rang back within few hours by technician who told me reg pack was looking like problem. He agreed to replace it and got car back next day fixed and valeted! Cost £196 which as car is a taxi is not bad. I cannot afford time off the road and local auto electrician wanted to simply replace alternator but could not do it for two days! Previous E220 CDI broke down couple of times with injectors and was fixed within 5 hours first time and 7 hours second time. Dealers may be expensive but for likes of me they are well cost effective and know what they are doing!!!!! Well done MB Sunderland!