Not sure about the number you supplied. I found "Call Now On: 0844 7705616" on http://www.dews.co.uk/contact/


Thomson gives this for the branch at the same address
Dews Garages Ltd
Northgate, Halifax, HX1 1XJ
Tel: 01422 395000

As it ends with zeroes, it could be the switchboard. Try asking them to put you through, or work your way sequentially.

or
Dews Accident Aftercare, due to be launched in February 2007, is a complimentary service powered by Accident Exchange
Try http://www.accidentexchange.com/contact.asp with lots of 0870. But I think there was a recent thread that might help.