I was in this industry for 20 years, so I know the scam. After my First 2 transactions, they got their fees and after my deposit, closed my merchant account. I called to find out why and the woman said, "our decision is final" and we "cannot explain to you why". The e-mail notification stated that it was due to section 2.1 of the merchant agreement.
As all information I provived was true and easily verifiable, I am at a loss as to the reason my account was abruptly closed. They are definitly NOT the cheapest card processor, but their equi[ment was update and that is why I chose them. If you do not want to repeat the hassel of obtaining credit card processing, do not use SumUp.