Well you've done your part trying to talk to him and sort it out. As soon as you can dispute do it. It exists for situations like this. Don't end the dispute on a promise either, can't reopen it. Wait till you get what you paid for and if you don't receive the item, you should get your money back.
Edit: Wanted to add if it hasn't been marked sent I believe it automatically cancels after 100 hours anyway iirc.
Edit: Wanted to add if it hasn't been marked sent I believe it automatically cancels after 100 hours anyway iirc.