If you paid from your credit card through Paypal, call your cc 's customer service line. The 1-800 number will be on the back of your card or on your cc bill.
Ask about a chargeback. Do this immediately. While cc's have longer deadlines than PP, they still do have them.
Now that you are aware of the 45 day deadline, if a similar problem arises in future, you will know to file on Day 42 at the latest no matter what the seller is telling you. Filing gives both of you a 20 day extension.