Ok well I have tried further and I have a kind of result which I am typing up for others who are in the same dilemma.

I phoned the 02476 602142 number loads and kept trying different combinations of options. Eventually I chose option 2 (SIM) then option 3 (inventory) The phone actually rang and a helpful lady picked up. I was told this was the warehouse. She took my number and tried to transfer me. I got cut off but somebody from the call centre in Ireland phoned me straight back. My queries were answered. I did protest about the cost of calling 0870 and tried to get him to give a direct number to no avail.

To assist with the search for a direct number for this 0870 line at least we now know it is routed to Ireland. One number I didn't try is Limerick operations on 00 353 (0) 61 443 777. It may be worth trying them as I suspect this is where the 0870 number is routed to.

If I find anything else out I will update this thread. God I hope Ofcom and the companies concerned take note of the lengths people like me are taking to avoid these damn 0870 numbers!