Hi I have a MKIII the control modual is under the right rear side panel and can be accessed by just taking the cover off. You have to look up inside. cost is about £80. sensors are about £40 from Ford. Sounds like it could be a module problem if no sensors vibrate. Get some one with a vag com to check for fault codes. I can let you have a list of fault code and a description of tests and a desicription of the system as a pdf file.