This is unacceptable, placing the onus on the customer, especially when the offending prefix number has not even been published for information.
It must be be for giffgaff/02 to block known (incoming) premium rate numbers but more importantly to prevent all payments to these rogue operators.
I for one expect to be indemnified by giffgaff for any credit balance losses. I say this because on my profile I have them blocked:
https://giffgaff.com/call-services Which Says:-
"Incoming premium calls and texts
Had enough of receiving premium calls? You know those numbers starting with 09? Or texts from premium rate adult or chat service numbers? Well, you can block those calls and texts here. Problem solved. To find out more about premium rate numbers check out our pricing page."
Any deductions from my balance would therefore be a corrupt payment to criminals.
How Vodafone deal with these crooks:-
"I accidentally called back a Wangiri number. Can I have a refund?
We don’t want you to be out of pocket as a result of these scams, so we refund all customers who have returned a call to a confirmed fraudulent Wangiri number. We aim to process these refunds within 30 days and we’ll confirm the refund has been applied by sending you a text message.
We proactively monitor the network for Wangiri scams, but to ensure we’re aware of your particular case please text CALL to 7726 free from your Vodafone mobile. We’ll reply by text to ask you for the phone number you’re receiving nuisance calls from. Please reply with the Wangiri number you called back."
"What’s being done to address this issue?
We proactively monitor our network for Wangiri activity and shut down new fraudulent international numbers and number ranges as we find them.
This is an issue affecting customers of mobile and fixed line operators around the globe, and we’re working with a number of different operators to reduce Wangiri fraud levels."