Neo Facebook ****mer

1. it does not seem possible to log a direct marketplace issue on the facebook app?? 2. sold a phone on FB, received proof of payment 3. buyer arranged collection via Uber 4. later sends me a message saying that they had paid another amount into my account by mistake will i please refund. 5, first they ask for e-wallet but i decline 6. then i ask for banking details, but would only refund once i confirm deposits into my account 7. next day i check and there is nothing there 8. this buyer rated our transaction on FB but i am unable to access their account 9. I have a number, which i think is a business number but my calls keep getting declined 10. i also have banking details that seem to be for uKeshe Payment Solutions 11. is there some way to contact the buyer via FB?