I sell local SEO service and have had a client on a monthly subscription of $300/month for 3 months. 14 days ago he paid for the third month and I spend his payment on guest posts and articles the same day. 2 days ago (12 days after payment) he said he didn't want to pay for the third month and demand a refund. I already spend the money, I do not offer refunds (also stated on my website) and he didn't tell me he wanted to end the subscription before he was billed. I told him I can't offer him a refund, but now he says he will chargeback if I don't refund him - I do not wish to risk losing my business paypal account. What can I do? It's totally unfair, he is even seeing good rank boosts this month and I keep just 10% of the payment myself.