-snip-
Could this be a system error? Or the system detects or suspects suspicious things, especially after winning a fairly good amount of rewards.
And sometimes gambling platforms will do this when their system detects a suspicion about the account.
If you feel right and don't commit fraud against bonuses, try giving some evidence to CS, especially regarding the winning rewards from sports betting.
And you can also include screenshots of the data proof or winning history.
If your evidence is strong, usually CS will apologize and the team will recheck, and if there is a system error, don't worry, the account will usually be recoverable. But again it must be with strong evidence.
I do not think that the system is an error because the Stake's team will know if that thing will happen and try to fix it ASAP. As one of the reputable gambling sites that have operated since a long time ago, Stake does not easily ban someone if they do not see a suspicious thing on the account or their member's activity. So it could be many things already happened to @OP but hopefully, Stake will check this issue and solve it right away so @OP can get his coins and withdraw the money.