When you overpay an invoice on Virtualminingfarm the pay you the extra amount you paid. What a nice implementation. And you will receive an email like this:
Virtualmining.Farm – Virtual Bitcoin Mining
You have deposit 0.00010000 btc
Currency Type : Bitcoin
Account ID : 5C75262511XXX
Total Balance : 0.00049391 BTC
From overpaid invoice
Best regards,
Virtualmining.Farm Team