Audit Stripe & PayPal Integration

I have several sites with Stripe and PayPal already plugged in, yet I’m not completely sure the setup is rock-solid. I’m looking for a payments specialist to sanity-check everything and prove that money flows exactly as it should... (Budget: €6 - €12 EUR, Jobs: API, API Integration, Debugging, HTML, Payment Processing, PayPal, PayPal API, PHP, Stripe, WordPress)