I would like to get advice on other similar merchant servics which offer zero chargeback guarantee since buying crypto by credit cards is very risky.
Cash 
It's not really a service, but it's the only thing (other than crypto) that's truely irreversible.You could investigate bank transfers. In some countries they're not reversible.
Also when the payment is made from a hacked account? Most exchanges ask for KYC on top of bank transfers, just so they know you really own the bank account you're using.