Witter Tow Bar height drop

(Moved from Forum Feedback)

I have caravanned for 23 years with 7 different cars and 6 caravans.Last May we changed our Citroen C4 to a new Citroen C4. We had a new witter tow bar fitted by one of their recommended dealers.  Unfortunately it was fitted too low and not to their own recommendations.  Witter sent another fitter in who rectified the problem.  Then in February our car was hit while stationary which meant the tow bar had to be changed.  We asked for the same fitter as before but this time he left it too low. Reluctantly he came back and sorted it.  However after our trip to France last week it has dropped by50mm. Witter aren't interested and the fitter who is on their recommended list wont come back. Have any other members experienced any other similar problems.