Paypal unauthorised transaction spam

I thought I had 5 very good clients, for a good 2 weeks they would each buy 5 things from me each week.

Now I discovered that this was all the same guy, he simply used 5 diffrent accounts and on a daily basis he is starting to create a dispute on every transaction claiming its "unauthorised"

This will turn my paypal balance from 2.2K -> -1K, I recieve around a 10-20% margin on each sale
Is there any way besides uploading emails with proof that would secure my money? If someone has a bulletproof method ill gladly pay for it (after succses ofc)