Doesn't matter what account type you have whether personal or business, if you are using paypal to receive payments from buyers then you pay a fee.
You don't get charged for a refund as long as the person sending it uses the refund option, but you will get charged if they send it using the send money > goods/services option by mistake.
Or if you meant you were charged when you issued a refund and not received one then paypal no longer return the fee that you were charged when your buyer paid as part of any refund that you issue. They charge you the fee as they have provided you with the service of processing the initial payment and the refund for you.
Advice is voluntary. Kudos / Solution appreciated.