When a payment is made using your payment terminal, it will be credited to your Merchant Account. You can find out more about receiving card payments here.
You can charge up to a maximum of EUR 5000 per transaction, unless your customer has a lower spending limit set on their card.
You can issue refunds to your customers via the merchant account:
Open the Vivid Money app/web-interface
Go to the Merchant account
Find and open the relevant transaction
Tap Refund
Payments in other currencies than Euro are currently not possible.