Good to see the problem solved, but next time you might want to use Electrum (which support RBF and CPFP).
If the transaction is flagged as RBF, then you can't use it to make instant bets or plays while it still has zero confirmations, for obvious reasons. CPFP would have solved the problem here though, as you say, except OP had no change outputs.
Did you miss this part of my post?
Good to see the problem solved, but next time you might want to use Electrum (which support RBF and CPFP). It could be useful when your transaction got stuck, but there's leftover which sent to your change address.
I wonder if it was a case of their algorithm making a mistake, or maybe OP is a long standing customer with lots of deposits and an account in good standing and so he gets the benefit of the doubt.
That "good standing" is quite a flaw! It means anyone can send some 1 sat/byte dust to his Roobet deposit address, and he'll be forced to pay an expensive accelerator again.
While new user might see his funds frozen or worse.