I used autowfit last month. he was about 50 cheaper than other local fitter and witter. He bought the towbar from witters. Did it on my driveway in couple hours so can do at your place of work or home
Email him and Chadwicks for prices. Witter website also does an online quote so you can check prices
Autowfit email andy@autowfit.com 07970 531001
Chadwicks email hannchad@aol.com 07917 061 438
witters website
http://www.witter-towbars.co.uk/