you need to follow the proper format:
Scam Report Format (Use it to make scam reports properly)you need to post proofs, start from the beginning: you deposited Z amount (post photo and deposit ID), then you won or lost (post photo of your victory history, then you withdraw X amount and it is still pending, then post a photo of your pending withdrawal and lastly, you contacted support, right? then you need to post a photo of your conversation with support. That way it will be easy for us to understand what is happening.
NOTE: I also recommend that if 7 days go by without them solving your case and ignoring you then you can raise a flag against them
Checking this section there are already 7 scam accusations against Betchain but on this particular thread
https://bitcointalksearch.org/topic/betchain-takes-major-winnings-away-5257873, Askgamblers was a third party to resolve the complaint although the dispute was in favor of Betchain, you can try to file a complaint against Betchain on Askgamblers if you have a good case the finding could be in your favor, the representative is not active here anymore but since the site is still up this thread will still have an impact on Betchain.
It's strange that the casino rep's account doesn't even have neutral feedback alerting these accusations, it seems that either they are very busy and that's why they take a long time to solve people's problems or they are very lucky to the point that no one leaves any feedback on their account