This is the info you should have at attempted to provide.

http://www.ehosting.co.uk/contact.php
mailing address

    * ehosting Limited.
    * 5300 Lakeside
    * Cheadle Royal Business Park
    * Cheadle
    * Cheshire
    * SK8 3GP

At which point a simple google with ehosting and 0161 produces

eHosting Ltd
5300 Lakeside Cheadle Royal Business Park
Manchester M1 3GF

United Kingdom
Phone: 0161 24 66 111

This may or may not work.

The office is in a Regus building.
Regus specialise in "out of the box" packages, including the thieving phone numbers which they subrent to their tenants. Unless ehosting have their own working BT, or other, landline installed, I doubt if they will know the true number to the 0870. And the rip off merchants at Regus aren't going to give it to you.

These are the main numbers for the building, as listed here, http://offices.regus.co.uk/locations/GB/Cheadle/ManchesterCheadle.htm

Main tel: +44 (0) 161 246 6000
Main fax: +44 (0) 161 246 6100

Bear in mind this might be reception, who might fob you off with the 0870.

However, looking here,
http://virtualoffices.regus.co.uk/products/default.htm#voplus

at the features offered in the callplus package, you may find your company is not actualy based there, but just using it as a mailing address. If that's the case, should you trust that company?

Call Plus – From £75 per month

Give your business an official voice with a dedicated phone number and professional business address:

    * Prestigious business address - Choose from 750 world class addresses, including over 90 across the UK, for use on your business cards, letterhead and marketing materials
    * Mail collection and forwarding – Mail, faxes and packages can be received and are either held for you to collect or forwarded to you via first class post or courier service - according to your instructions. Total postage cost plus 20% of the postal cost as an admin charge