Trakie

Hi. My first question is that the central locking has got a mind of its own. The locks keep going up and down on their own accord. The passenger door will not open anymore to get the panel off to have a look. The lock on the passengers door doesnt seem to be going up all the way. Can anybody help. The second question is do the drive shafts on both sides need changing every couple of years. The garage has told me this when they were changed for the second time. Is it true or are they ripping me off. The reason they were changed both times was because there was a knocking noise when going round corners. :o