Left Airpod not working.

I bought Apple airpods through amazon back in January and both were working fine but now the left airpods is not working. I have tried cleaning, and resetting the airpods and my phone and still only the the right one works. I contacted Amazon to see if I had a warranty on the airpods but it expired back in February but they said that Apple has a year warranty on airpods and that I should contact them. I did contact customer service but they are wanting to have me pay $75 to send me a new airpod and that I should send them the broken one back. Why is Apple having me pay $75 when it says there is a year warranty on Apple airpods?