A blockchain entry is the only way to really prove a transaction has gone through, you may be able to find a reference for this in the wallet you're using.

It's a good community but it's not without its parade-pissers either, although it's hard on genuine new sellers, id advise against giving anyone the benefit of the doubt when it comes to reviews and lack thereof, there are a few scammers about who will deny all knowledge, especially if you don't have a blockchain entry to back it up