What is the "promised time" anyway? I mean, we would assume it's semi-immediate, but I don't actually see it promised anywhere....

Also, the bitcoin payment method goes through a third party, bitpay. You might want to contact them too. It is possible that something is wrong on their end and oasis never got their money(which is probably in USD as opposed to bitcoin). I'm not sure if you'd get anywhere asking oasis to refund you in bitcoins, they might not have any and we don't know what kind of contract/agreement they have with bitpay.