The bank account closed, when we switched to a new lender, therefore we no longer had any use for the debit card linked to it. Pretty sure we destroyed it for security reasons. New bank account with a new lender has a totally different account number, sort code and debit card numbers.
Since my last post, we are a little bit further forward. Our old bank (disputes team) have confirmed today that anything that was refunded to the old card number would have just bounced straight bank to the issuer (Ticketmaster) as the bank account is closed and has been for over a year. The switching facility "bounce forward" was only in place for direct debits and standing orders, not refunds back onto the debit card. They're not being that helpful to be honest as basically, as soon as the account closed, they seemingly obliterated everything. They even asked us for the old card number if we still had it!
Our new bank have also confirmed again that no refund has been made to them. They have checked their error suspense account - nothing. They told me that our old bank need to raise a dispute with Ticketmaster for lost/stolen funds but they have refused to do that - they just keep parroting "the account is closed".
The ARN, which Ticketmaster eventually provided, proved absolutely useless with both.
So, I've gone back to Ticketmaster with this information today and basically said you have my money and I'm going to report you for theft/fraud if you don't make alternative arrangements to give me my money. I've also found an organisation online called STAR, who I'm hoping will be able to help. I'm going to call them once I, no doubt, get another stalling e-mail back from Ticketmaster wanting letters from the old bank, new bank, any bank that I may choose to bank with in the future, my inside leg measurement and the moon on a stick. Our old bank told me to report it to Action Fraud, which I'll do if I don't get any joy with STAR.