Could be mate, the regulators go as well. its not a cheap fix so get them nailed down with a diagnostic. If they find no fault, make sure you document it all in a diary and the dates you visited, just so if it does it again out of warranty you can give them the dates you reported it. All VX service computer are networked, they can print off all the work that has been done on your car from any garage as long as its in the VX network.