Visa Debit Transaction - Refused Refund

Hi There! I'll try to keep it direct and to the point...

On June 1st the Visa Debit systems went down across Europe as we all know.

I went to go do some shopping that night when it had all happened and had my transaction refused (the bloke in the shop informed me the systems had been down all day). Tried to do shopping in another store and it declined again. Tried to draw the money from the bank machine but didnt have the available funds at that point cause I was charged the very first time even though it had declined.

Contacted my bank at this point and they informed me I'm not the first person to call with this problem and the money would reappear in my bank account within a few days. After nearly 3 weeks later and multiple phone calls, the money is still no where to be seen.

The bank themselves have said that it HAS bounced back into my account even though it isn't showing on their systems and I cant dispute it or get a refund from the bank because it isnt actually showing on their systems (If that was the case, I would have thought the balance would change even without an actual transaction appearing on the account to say that it had bounced back in?)

So after speaking with the bank and basically being called a liar and told to go away; I'm at my wit's end and want some kind of resolution to the matter. Where can I go and escalate this to try and get my refund? Any help would be appreciated.

Thanks!