What about Binance P2P?
and there is a member from Nigeria who is very trusted CryptopreneurBrainboss, he have an exchange service, from Altcoins to Nigerian Bank Accounts, indeed it is not for the service you need but maybe with proportional fee he is willing to help you, just wanted to let you know, and also not knowing if withdrawing from a gambling site directly to a bank account in nigeria is safe, hope you can withdraw the money.