Is there really no protection for sellers who have raw costs?

I run several hourlies involved in app promotion services.

i can deliver app installs to users apps.

Normally this is ok, deliver the installs and get paid, leave feedback, great.

But I have also had several buyers who then decide to get clever and then not pay, complain that they arent happy for whatever reason (on being that lots of users uninstalled their app - which is actually not wrong as we dont promise app retention in the work description).

Then they request PPH for a refund OR they do a bank chargeback and hey presto, they get their moneyback AND they get free app installs.

So where my protection and cover, wheres my benefit with working with PPH and giving them 22% fees?  Whats the point of the escrow?

If the seller is saying I did not deliver the installs then why does PPH not request screenshot proof from the users app console stats?  Because if they did then they could clearly see the installs were delivered and they have no grounds for a refund.

These and other jobs cost us sellers money, we have to pay to promote and pay for bids to get users.  We can not get this money back once paid.  However the PPH escrow or support team is not providing us adequate cover to comfortably do this work...

The problem now is when i get my next app install order, i have to bear in mind that again the buyer will get a full refund at my expense, so really do i want to sell and do the work?