Hi all I’m back biking after a 26 year lay off I purchased a bmw r1200gs it was all going great , took to it again no problem. Put couple thousand miles on it but was worried about it having no history of been serviced for some years although the guy I bought it from said it was done . Anyway I decided to bring it to a bmw workshop and asked him to service it and change the oil in final drive . He recommended not to change oil in it as bearing was worn and it would leak but he had final drives for sale and he could fit one of them we agreed a price and he done the work . When I paid him and picked up the bike he told me the abs sensor wasn’t a match but to give him a few day he’d sort it with his tech guy, 3 weeks later he said leave bike in for a few hour to sort it . That was three weeks ago the final drive and sensor wouldn’t match I asked him to put original drive back on and he still can’t get the abs working , wants to buy the bike now but only offering trade price and I cannot get a replacement for that price and we cannot agree on price for newer bike , he doesn’t seem interested in fixing mine anymore. What do I do now no bike load of hassle.