I used the
find an alternative number option on this site, which gave me an 0121 5216000 number. They told me to dial the 0870 number. I explained that I wasn't able to and unless they could either give me a geographical number for Staines, or put me through, then they would lose a booking.
They put me through, and I spoke to a nice man about a 'pretend' booking.
I asked him for a geographical number to call him back on once I had made up my mind as to whether I wanted to stay there, and he told me simply to dial the 0121 number and they would happily put me through.
Always worth checking the
'find an alternative number' option on this site and if you find a number, then always worth giving it a try