Got onto the chat and had loads of evidence from the payment providers and screenshots. Asked for it to be escalated to the IT Team and I'll be happy to help troubleshoot the issue with them as its impacting loads of people I know.
They also came back with the following which is interesting:
"the billing address on the card using to pay needs to match to the address of the person you are purchasing for if you are not purchasing for yourself in the
same transaction if you are purchasing for yourself and others in the same transaction on your account the payment will go through as your billing address
matches the one on your account"
"Recently, rules have been put in place that the person who is the owner of the ticket, the address on the card needs to match the address on their account"