I've had a similar experience- something sold for a deep discount (MIDI controller), received something else entirely (cheap bluetooth speaker), and was told to keep it instead of sending it back and sell it to recoup my costs while they refund 15%. I recognized it as a scam at that point and saw that the email I paid to was different than their support, and when I replied asking for 100% it was yet another email.

Luckily for me, taking it up with PayPal got me my 100% refund, but I was nervous while they went through the motions of asking the seller to settle up with me, which I had to approve or reject, and then PayPal would review further. Screenshots of everything, showing the weird random email addresses, and the fact that their website didn't exist anymore landed in my favor.