I was going to write the exact same response. One day I'm going to write a blog post because the overwhelming response has been very hostile. Even when companies advertise that they do it.
Here's my experience so far:
Adyen.
Overwhelmingly hostile to startups. All telephone numbers get routed to support. So if you call sales, someone in support answers. The individual who answers the phone also has very basic knowledge of their product line.
Each office that I contacted (US, Europe/London and Europe/Amsterdam. All gave differing reasons why I was not suited. Where it last ended, because I wasn't doing $1m a month. I was not a suitable candidate for their services. Even though someone in the London office did mention I could email my business plan in, although there was no chain of custody and who knows who would be looking at it or when they would come back to me. I think they were really saying that to make me feel better.
So really. How can I get to $1m/month, if I cannot start?
Braintree.
Had good response with braintree, was about to pull the trigger. But then their marketplace solution has been superseded by paypal's new offering of marketplaces.
Paypal.
Called their business team and been forwarded to partnerships. Can't get a hold of their partnership team as they don't have an email or telephone number. 14 days has passed by and all I'm looking for is a simple yes or no. I have filled in their contact form (3 weeks ago) here: https://www.paypal.com/us/webapps/mpp/partner-program/contac... But never hear anything back.
Stripe.
Even though this was my initial provider to go with. It's currently a non-starter and I am leery to approach them. With no actual phone number to contact them on and previous email exchanges being less than steller and not having someone who actually could understand the business model. Note: Shopify is doing the same for heavens sake (yes I am frustrated lol).
Additionally, I am not in the US, so there is also the extra hurdle of having to go through stripe atlas. But again, not really wanting to forward my business plan into the void.
If Stripe had a phone number that I can call, I would investigate that possibility. Can't really understand when I can call lots of other finance companies. I can't get hold of Stripe directly.
Worldpay.
Didn't understand my business model. Even though they promote themselves as being able to deliver complex solutions. It was determined that they could not support my marketplace.
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Finally, if anyone is reading this and is from an acquirer in the US or perhaps from the companies mentioned above. Or perhaps a partner of stripe-atlas so I don't have to wait two weeks/direct contact. Please let me know. My forecast is that there will be a tipping point in the first year where I will be doing $5m a month.
The sad part here. The development of the platform/marketplace. This was the easy part. The difficult part, is finding someone high-up enough the ladder to see that they will be on-boarding a company who their closest competitor is now doing $100m a year. Where that competitor is tiny in the overall competitive space.