It should be fairly easy to log into your Paypal account and find the outgoing transaction. It'll be in USD instead of your own currency so it should stick out like a sore thumb (it'll also be for a large quantity of money).
Once you have found this transaction, open it then simply click "Request a refund". Once you have done this, send a message to MVP and let them know that you have done so. They will then be able to action the refund and the money will be back in your paypal account within 5 days or so. Once it's back, transfer the money to your account.
I'm guessing there is a bit of a language barrier here as the last communication, to me at least, clearly states that they will refund you over paypal? I'm guessing the initial payment must have been paypal or they wouldn't have said this? If you are adamant (prince charminnngggg) that it wasn't Paypal, then find the transaction on whichever of your accounts you believe it to have been from and let them know that it wasn't Paypal.
As much as the customer service has been horrendous, you haven't helped yourself by having no idea where the money came out of or how you paid the bill. These are very simple details that need to be known when requesting funds.