Ask HN: Best Solution for Aggregation Payments?

I was told by Paypal's compliance department that my startup was not allowed to use their service since it considers my business model an aggregation site, where I would take payment from one party and release it to two others after an action is performed.

Amazon's FPS Aggregator/WebPay service requires users to have or setup an Amazon account, which is fine for some users, but not the best solution in this case.

I need my users to have an account that they will add funds to in order to pay for items, and also need options as far as getting paid back out on the selling side (online, snailmailed checks, direct deposits, etc.)

Are there any other recommended payment aggregation services that might be a good solution for this?