I bought my daughter a new Golf 118TSI last September. I paid $1300 for a RNS 510 on ebay as soon as I got the car. I had the unit installed but couldn't get the map working. My local dealer (Solitaire in Adelaide) somehow got the map working but the performance of the unit has always been a problem. Specifically, the satnav takes about 20 min each time it starts to find enough satellites to know where the car is. As a result, it is pretty useless. This week the car went back to Solitaire for the fourth or fifth time but still no joy. Instead, I was told by the service advisor that because the car lacks the sharkfin antenna, the RNS 510 will never work properly. I'm not sure what to do next. I've asked a friend with a car hifi shop to take a look at it but he's not a VW expert so I'm not overly optimistic. On the way to drop the car off today, the map disappeared - this hasn't happened since the map was first fixed by the dealer.

Anyone had similar dramas?