This is an all too common request, and because it is impossible to comply with when the card in question has been destroyed YEARS ago, it makes casinos look like they are using the demands as a ruse not to pay. Banks are not in the business of confirming accounts that have long since been closed, as once the bank is satisfied that there are no outstanding matters, the closure goes ahead. If there IS an outstanding matter, the bank will NOT close the account.
Even the sending of a confirmation letter is not a universal practice, and even if one could be obtained when needed, it could take WEEKS for the bank to send it out, so in effect, FL are telling this player the money is on hold for as long as this takes. With my experience of "big business" here in the UK, he may not even get this letter without having to request it several times, and then badger them to hurry up. It is made more difficult since he is no longer with the bank.
I had a similar issue, unrelated to casinos, but where a card with a loyalty element was closed down because the companies concerned decided to pull out from running the offer. Some points went missing, and whatever side I contacted said "raise it with the other, we no longer support the product". Even after only a year, neither company could retrieve the data in order to explain what had gone wrong, and to correct it, and neither was prepared to be the one to deal with tracing back the issue. They then closed down the support departments that had dealt with this altogether, making it impossible to contact them. The issue was never resolved, but was not worth anything like 4K. I STILL have an image of front and back of this card though, from it's first incarnation as a VISA card, as I used it for a time at casinos before they switched to Mastercard and put a stop to it.
Some players have had even worse issues, as they have been asked years later for copies of a GIFT card once used. Such cards are only good for the amount on them, and cannot be topped up, so are usually destroyed once used. There is often no CS for gift card holders either from the issuing company, so getting a letter confirming the details of a specific gift card is impossible.
Players can partly protect themselves from these "out of the blue" demands by routinely making the copies of the cards when they first use them, even if no casino has asked for them, even gift cards. They should then keep these images "forever", such as on an archive CD or DVD along with similar long term files. The same could be done with letters from a card issuer that demonstrate that the account behind a card has been closed. Most players will never use these archives, but because such requests are unpredictable, having the data to hand can make such a request no more difficult than supplying current documents.
I cannot see why they need a 2 year old card though, as they are no longer in danger of chargebacks from it, even if the account was still open.
eCogra will see the ridiculousness of this request, and by taking such an approach the casino has left itself open to having eCogra poke it's nose in, and make judgement. This can leave a "black mark" on it's file with eCogra just as not paying a bill leaves a "black mark" on someone's credit file. CS should have taken a more realistic approach, and management should have told the processor not to be so unreasonable and accept the current set of documents.
Rather than going on about it, the OP should have left it with the first post, toned down to be a tale of woe, not an accusation of deliberate intent, and sent CS the "14 days" formal email informing them of the impossibilty of the request, and that as you had reached "deadlock", you would make a formal complaint to eCogra after 14 days.
I can assure you, IT WORKS! Prime casino tried to jerk me around over a £500 withdrawal by launching an investigation, even though I had been a long term player and on the VIP list. I sent the email on a weekend so they had it for the start of the week, and within HOURS they had "concluded their investigation" and paid up. It seems they didn't want eCogra asking questions and finding out they didn't really have a leg to stand on. If they DID have anything, they would have presented this to eCogra rather than pay up. The 14 days is counted from when things stalled, and if you can get the casino to send you a "deadlock" reply, such as refusing to back down on this request, you can go to eCogra straight away.
Unless FL have reasonable grounds to believe they are still at risk from something going wrong over this long closed card account, they are not going to want to embarrass themselves in front of eCogra. Contacting the rep today so that he has the message tomorrow may well make progress such that the need to go formal with eCogra or a PAB is removed. FL can still be "punished" through the loss of your custom, the same "punishment" I meeted out to Prime casino. I also uninstalled Ruby Fortune around the same time, as Palace Group did the support for Prime, and so I held them partly responsible.
Good stuff, glad you got it all sorted. 
