Good question, and not one i have the answer to, ill have to go back and ask them. Id also like know know, as ive never had rear sensonsors before, is how come some people seem to have towbars fitted and have no issues with it setting the sensors off and spome people do?

All it said in the email was this;

Thank you for your e-mail.

The price for a fixed flange towbar with single 7pin universal electrics is £250.00 including VAT and fully fitted at home or place of work.

For 7 pin dedicated electrics the cost would be a further £150.00

We fit A1, Witter and Westfalia towbars which are fully guaranteed.

Please note that if your car has parking sensors and you get a fixed towbar, it may interfere with the sensors so we advise to go for a detachable tow bar. If your vehicle is still under a manufacturers Guarantee, we advise that you go for the vehicle dedicated electrics.

Haha yea. Can't say I would be reversing either. It's only a 5 foot camping trailer that I'm towing, I had a flange towbar on my mondeo but that didn't have rear sensors. I read somewhere, maybe on here, that it was more the position of the electric sockets that set the sensors off rather than the towbar, and I have seen plenty of smaxs with flange towbars fitted. So who knows. Any smax owners on here that could say either way?