Hi
First I would send a written complaint to CW head office by recorded delivery. See CW website for complaints procedure and address. I don't think you will get anywhere dealing with the CW shop or phoning customer services. For companies like CW I would always complain in writing.
If CW do not provide a satisfactory response then you can go to Otelo. http://www.otelo.org.uk/pages/4howtocomplain.php
You could also contact Consumer Direct for advice. http://www.consumerdirect.gov.uk/
I have heard that CW like to stitch up their customers to make a sale.
Good luck
Huckster