The RBS actually bought Worldpay five years ago.
I would be interested to know why you try to avoid them?
You would have done better to have used Paypal in the first instance. The "more professional" providers always seem to make things so difficult for clients. It would also have been cheaper and much more efficient with regard to the set up. I don't know what's happening in the US but in the EU Paypal now has bank status. Watch them go! There are so many advantages in Paypal for start ups and I don't there are any real problems with public perception anymore.