I know that they make large payments and that they probably have few payment problems and that this is probably due to internal organizational issues and not because they don't have money or don't want to pay. They have money to pay, but in your case the employees don't seem to want to solve your problem because it doesn't cost anything for them to tell you whether they approve or disapprove your documents so that in case of disapproval you can correct and submit again. So create a scam accusation because maybe things will be resolved quickly.
I really think that there is a problem with their internal organization. Some departments in their organization process customer problem very slow. I've been waiting their answer about my case for 2 months (
https://bitcointalksearch.org/topic/resolved-is-it-possible-for-duelbitcom-to-retrieve-my-wrong-deposit-5465827) and haven't received the answer yet. I still contact their support agents every week but they only tell me to wait, there is no update for my case. Of course, my case happens due to my mistake, but I think that at least they should have an answer soon for my case. From comments in my topic, I know that other gambling sites take less than 1 week to give the solution for the similar cases (Take an example: stake and roobet solved the problem within 1 hour)
You will Just have to be patient, atleast, that is all you can do since I personally see or feel that you don't have much of a choice, duelbits can decide not to help you with the claim that they do not have the private key to the network where you sent your coins to, and there will be absolutely nothing you can do about it.., the mistake is entirely yours and as unfortunate as it may sound, you are completely at the mercy of duelbits right now, they can decide to help you and they can decide not to help you..
So just keep reminding them and be patient, the issue is something they will help you solve at their own convenient time, I will only advise that you take the advise of AbuBhakar and put into consideration., find a duelbits representative who can help you be in charge of the case until it's resolved.