jamesbond's advice would seem to be the best bet to achieve a result so far.
I suspect that this one will only be known by the company and its telephone provider, and that we're unlikely to be able to sleuth our way to it.
I have removed the entry in the database which gave 01484 664735. As Gyro has said, there is a recording on it redirecting to the 0844 number (complete with the misleading "Lo-Call" term).
I came across
this thread on PCSpecialist's own forum where the fax number has been given as 01484 667140.
Calling the 664735 number gets through to the recording, and when one presses *, it prompts for an extension number. It may be worth more investigation, but it didn't seem to be for putting calls through to other extensions, more leaving voicemails.
However, I did find out that they have three-digit extensions, and that 100 and 102 are valid numbers.
I get the impression that these are just odd numbers they have, so it's likely that they've simply aquired another (unrelated) number to sit behind the 0844 number.
"01484 664732" would appear to belong to someone else.