Is that $73, (I am going to assume it's 73 USDT) a total that you deposited in multiple deposits? For instance, $10 first time, $20 a second, etc.? If that's the case, it might be the reason why they didn't credit any free spins to your account. The promotion is available only for the first deposit that you make, and that first deposit has to be at least 30 USDT or the equivalent amount in other cryptocurrencies as stated in their terms.
The 73$ USDT deposit has been made as a single deposit. So, there is no reason to not provide any free spins. Also, as they have given the free spins they must have the details of the free spins. If they don't have details then it is also a scam in the guise of free spins.
There must be some additional explanation and reason why they aren't able to help. So, you told them that your free spins bonus was never credited to your account and they just said, sorry, there is nothing that we can do, bye! How do they explain that you didn't get any free spins?
I am in the same way as you. I have told the same thing to them and they have to explain why I have not received the free spins and how I would be eligible for the free spins.