I have been using CoinPayments since 2014 for all my cryptocurrency payments and wallet service. Great company and legit in all respects. They won't work well for your needs IMO though.

CoinPayments has the motto, "by the time you're ready to cash out into FIAT you won't have to." They are all in on crypto and don't support government issued currencies. They do have an integrated API that works with FIAT settlement providers like Coinbase in the US and CoinMotion.

I know they are working on a partnership with a third-party FIAT settlement company to make the process smoother but haven't heard a date yet.