The Mégane II Owners' Club

Hello I’ve just bought a 2007 megane 1.5 dci dinamique, previous owner told me that the alternator had been changed but was slightly the wrong one, there’s a plug with a single pink wire with nowhere to go!
He tells me this throws up a battery fault now and again, is this correct? Also my pano roof doesn’t work, it moves up slightly ( 10mm) but then retracts, any help guys