I recently made a purchase for 2 items and the vendor sent me a single item that wasn't either of the 2 items I ordered. I messaged the vendor as soon as the pack landed and let them know about the mistake. It has been 24 hours and I haven't heard back. This vendor is well known for being quick to respond to messages and was very prompt in getting back to me when I had questions about the order before placing it. So although it has only been a day the lack of a response seems odd.
I don't want to start spreading negative info on the vendor if they are going to take care of the issue. How long should I wait for a response before leaving negative feedback and/or a negative review on here?
Wait another few hours then dispute. Either way you should dispute it but it is usually more polite to allow 36 hours to respond.