I will take a stab.
This site is new:
http://www.pornnerdnetwork.com/
Not sure if you are promoting that site for signups. It's put together pretty well but I have a suspicion that no members area exists in that type of tube format... making members have to log into each site differently.
If so, my suggestion is to dump all your vids into that site as well so members log into 1 site. You can create a channel for each site and it would be well organized, all in 1 place.
Or it could just be a select few people decided to chargeback around same time.
You will never know why a refund or void is made because unfortunately you still are not doing that yourself.