Isn't it possible to rebroadcast your transaction and add more in your transaction fee if you think that the low fee is what's causing the transaction no to go through? I read it somewhere in the forum that it is now easier to do with version 0.13.0. I am not sure if what I read was right. If anyone knows the correct information please explain in more detail.
Correct, you can easily create a new transaction using the same inputs as the original transaction, the "main" output still going to the gambling site (in this case), but send less change back to the change address (in other words: add more fees).
KnightDK has made a pretty tool to assist anybody who wants to try this, or i can help you out to (if you want to)