Where can I find a safe, stable, and newbie-friendly merchant account service?

[Sarah]

I have taken on a new contract job that will require me to accept credit card payments online or over the phone. I absolutely -can not- afford to lose this job offer as I have already invested a lot of time and money in attaining it and preparing for it.

The developer I am working with had recommended ProPay as a merchant service because they base most of their instructions on the use of ProPay. I went ahead and made an account there, but when I went to process my first orders I had found that the service had been manually cut off. No direct reasons were given, but I suspect it is because someone went and ran a manual personal credit check on me.

I have a credit score of 600, due to a series of unfortunate events where my family decided to abuse my generosity. Of course, you can not explain this hard-lesson-learned to banks.

This said, does anyone have any suggestions for a merchant account service that I can use that will accept me without a credit check or with a score like mine?

It needs to be newbie-friendly, as I have never had to accept payments before or have an account. It also should allow me to send invoices and allow customers to pay directly online; there should not be a very low cap on the monthly transactions, because I do anticipate a large number of sales. I can pay for any fees, so long as they are not predatory and rediculous.