as far as I am aware if you have been billed for the call you have the right to ask your telecoms provider the details of that number. If they refuse to give you the details dispute having made the call.
I cant actually find the number you want, this is all ive got, hope it helps a bit
0906 numbers are usually favoured for "Technical support" helplines, competition lines, and other services where the value is in the content of the call information.