Hello @steele5822
It sounds entirely probable that your seller is attempting to time you out by stringing you along until you can no longer make a chargeback via your payment provider.
If you have online banking then simply log in to your bank account, find the original transacton entry, and look for the chargeback option/button/link.
Your bank will usually require you to prepare a short, concise statement regarding the transaction and failure of the seller to provide a refund despite the return within warranty i.e. what happened and still no recompense.
Screenshots of the original purchase here or other receipt, the proof of posting, tracking page which proves delivery, the promise in writing by the vendor to refund, etc., can be uploaded to the claim.
Should you not have access to online banking or encounter any difficulties then do contact your bank ASAP, either in person at your branch or online chat, and do use your browser by typing in the name of your bank followed by "chargebacks" and read the information on an official page... forewarned is forearmed.
Do not delay any further, and good luck in your endeavours.
