Use of a premium rate (or any high cost) number as CLI is an example of "persistent misuse of a telephone network or service" making the caller liable to use of the same powers that Ofcom used against Barclaycard last week.
I cannot promise that any action will be taken, but this should be reported to Ofcom.
The relevant page in their complaints section is
here. You could phone them on 0300 123 3333.
It is likely that thousands of these calls are being made and if everyone reported them, then there could be some chance of action. I know that some may believe that the chances of anything being done is very small. All I can guarantee is that Ofcom will do absolutely nothing if nobody reports it.