I use eBay and my own site (hosted by Wix) to sell a virtual service with uses PayPal as the only payment option. Since the virtual service contains no physical item that gets dispatched, protection against fradulent claims can be quite complicated sometimes.
My main concern is that buyer's are able to chargeback on their bank account, and will 100% get their money back on PayPal with no questions asked, and I get no chance to prove myself to the bank that they are making a false chargeback. PayPal doesn't assist the seller in being able to contact the bank to deal with the chargeback directly, and only offers to payout themselves if you can provide proof that a physical item was sent to their address (which of course is impossible).
What is the best way to protect myself against bank chargebacks? Perhaps moving away from PayPal and using a payment service that allows me to directly respond to a bank chargeback, (if a service like that even exists?)