The timing chain doesn't need changing. If it does, then the cost is so great that you might as well scrap the car, but I have never ever heard of a BMW needing a timing chain. Transmission - is it manual or auto? If manual, the oil can usually be changed by siphoning it out of the speedo drive aperture. If auto, the job needs to be done by a specialist, by dialysis, and has to be at the right temperature and pressure. You need a member of www.fedauto.co.uk