Months?
Too late.
EBay has a strong Buyer Protection Policy, but disputes have to be opened within 45 days.
The Resolution Centre is up there in the top right hand corner, under Help and Contact, on the drop down menu.
You have only 60 days to leave feedback. The most effective feedback is calm and factual.
At that time,you will be asked to leave Detailed Seller Ratings. A normal boring transaction gets Five Stars. The lowest mark is ONE STAR. No stars is a Free Pass.
Go to the credit card you really paid with. Call the 1-800 number on the back and ask about a chargeback.
Do this now.
Credit cards have longer deadlines but they do have deadlines.