Well, it has only been 5 days already but I think that given how big the amount is being frozen, they might be trying to make sure that everything is right first so there's no other hassle when they finally unfreeze your account, I mean I would be suspicious of this amount too. I don't think Stake will risk their reputation just for this amount, they have big sponsorship already, and this won't be their downfall hopefully, be patient and don't be quick to judge and try to contact them again if possible but not in an annoying way.