Can anyone help me understand this paypal message

[Cycnic]

Hey

I sold something digitally on a video game to someone, about 2 weeks ago he regret buying it so he refund the money on paypal, I told paypal that this is a false refund and proved them that I actually gave him all he asked for (* he said  to paypal it wasn't him that bought it*) 

Pretty much about a month after, I finally got an answer from paypal but I don't understand what they are saying.

My account is currently on debt (about 400$ debt) because I already used the money he payed me..

this is what paypal wrote to me:

[InfernoPP]

It means that the buyer asked his Credit Card Company to dispute the payment. So paypal is basically fighting the case with the Credit card company