I am looking for zero chargeback merchant services,but seems like some of these services charge too much upfront fee,like simplex.That kind of fee is for crypto exchange,i think.

Right now,I have many clients who buy Bitcoin  from me,but my main payment method is only paypal.I cant accept big payments due to its much higher risk.Many cliesnt want to buy by credit cards.

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.

any advice is appreciated