Did you have the car hooked up to a diagnostic scan tool to check for malfunction codes
If not i suggest you have the management system checked for malfunction codes . you may have a bad camshaft sensor but the malfunction code will confirm this or if another issue causing you this problem
The cost of having this done is around 1hr shop labor time . if shop has £50 rate, then count on £50 ..
If they confirm a bad sensor then depending on the sensor location and time to remove will be the deciding factor .some sensors need only a few minutes and other a lot longer .
Please get back to me with the reply button and not the poor or bad service rating , so i can get back to you with further assistance with this issue or offer assistance with another expert .Rgds Greg