Warranty repair

I contacted Dell to report the fact that my battery wasn’t charging. After troubleshooting with the technician he determined the port for the power cord was bad and needed to be replaced. He sent me a box in which to return the laptop. I told him I could not send the laptop back until I finished the class I was taking which would be about 10 weeks. The technician said it was fine and that I could return it after my class finished. Lo and behold when I sent it back to dell, my ticket had been closed and now I’m told it was out of warranty and I would have to pay for the repair! I will never buy another Dell product, period.