Venmo is instantly reverisble much like credit debit. This is one of the most DANGEROUS ways to sell bitcoins and is favoured by scammers. We discourage using Venmo unless it is for very trusted trade partners.
So I have asked for my bitcoin back and he has not returned it after the venmo payment failed and the money was returned back to him. Have done good business with the past but until he starts responding to my messages I have no choice but to give him positive feedback. I am short $300 in bitcoin due to this issue.