Still going on - received a call from this number tonight at 23:00. It didn't wake me up but it did wake up my wife in bed!
BT offer a Choose To Refuse service which allows you to block up to 10 incoming numbers.
That might be your quickest option, as BT have no control over who rings you.
If you place the order, it will be applied within 24 hours. The first month may be free, check the page for details.
This seems to involve of a lot of people getting one call, rather than some people getting a lot of calls. If that's right, Choose to Refuse won't help.
Of course BT can't stop anyone making one nuisance call, including those from the kids and their mates when they press the wrong contact on their mobiles after a night in the pub. But a lot of complaints about the same number needs a look, and StephanieG has already said they are on to it.
Lots of people receiving calls at unsociable hours from just a few numbers. If BT were serious then they could block these. Of course, BT makes money out of carrying the calls and can charge us if we are forced into using its blocking service.
Result = increased profit for BT.
Result = 2 disturbed nights for my wife and me but, hey, who cares when there's money to be made.
Oh to be free of this odious company...
If you bother to look at the background, you will find that the two Birmingham companies involved claim to have been spoofed, and are working with BT's Fraud Department's investigation. The issue is thought to be abroad.
Hardly a matter in which BT is acting odiously