Mercedes-Benz poor after sales support

Mercedes-Benz can not supply cars with parts in South Africa . I have been waiting four and a half months for a wind screen and still they can not support me . What if I could not use my car for this period due to the Brands bad support. The feedback from Mercedes-Benz is also not happening with each person that I talk to passing me onto the next one Mercedes is no better than any other cheaper brand from any other country , in actual fact I think they are worse