VW Sharan 2012 Tow Bar fittings

I have just had a detachable witter towbar fitted through my local VW main agent to my 2012 VW Sharan. The installation was alright except that I was left with a large slot around the fitting - really spoils the look of this .

The fitter, who was a local witter approved installer, said that there was an alternative arrangement wherby a spoiler and cover could be fitted as an option. He referred me to the Westfalia Towbar website (not sure why the witter site doesn't cover this) which seemed to show such a fitting and gave a part number.

The VW agent could not trace anything except a panel like the one that was already on the car, so I am at a loss where to go next.

Has anyone had a towbar fitted and had a similar problem and found a solution?

Thanks.