rechrome

hi all, quick question regarding my W212 E63's exhaust. I want to get them re-chromed as the finish has come off. I've polished them with cleaner but does nothing as the chrome is no longer there so they look black. I was wondering if my exhaust tips are bolted on or welded? reason for...

My exhaust tips on my SL appear to be painted and are in a bit of a sorry state. Can anyone recommend somewhere to get them re-chromed, and preferably West London area but nationwide is fine if they do a postal service. I phoned a couple of places I found online but neither seemed interested...