Advance Products home page isn't loading images from the server:
http://www.advanceproducts.co.uk/
The dates at the bottom of that page suggest that it hasn't been updated for two years.
Trying to access any secure web page on that site results in a warning that the security certificate is out of date.
The terms and conditions page makes no reference to the company being 'limited' (or that 'Advance Products' is a trading name of another limited company) and the Companies House website lists 'Advance Products Ltd' as being a clothing manufacturer in Dewsbury. That suggests that the 'Advance Products' you refer to is, or was, a private trader.
Nominet's 'WHOIS' directory shows that 'advanceproducts.co.uk' is registered to an Ian Burrowes who has kept his contact details hidden by claiming that he's a non-trading individual. (That's both illegal and unethical for a bona fide trader to do).
Churchill Property Management Co Ltd is currently trading from 141b High Street, Loughton according to this page:
http://www.city-visit...ughton/surveyors.html
You've already told us that the phone line is dead.
It would seem safe to say that Advance Products no longer exists (if it ever really did).
Chris