[Warranty Woes] Rep said my warranty was extended, actually wasn't

Back in January - March, I had an issue with a M14X R2 that warranted a replacement. There were several issues in getting that replacement, mostly over how one representative would say that I was not the owner of my machine. Then through several weeks of trouble and poorly coordinated and dropped calls from Costa Rica, I was informed that since I got so much trouble for what happened and that my warranty was ending, my warranty would automatically be extended for a year. I figured that it was all over and I was happy with it.

As early as July, I've had issues with the unit I received and it's getting more and more to the point that I am going to be unable to use the system. The service tag apparently says that the warranty is expired. Calling Dell has resulted in refusal of service because I apparently never owned my system, and I don't know what to do now.

Issues with unit now:
- Battery won't charge past 77-79%
- Port is loose
- Pixels are dying en masse

All of this I've deduced to just be a bad build. I don't use it extensively, I use it for office work and school for the most part, and I game for a few hours in a week. I take damn good care of my unit.

What should I do to get this resolved if different reps have led me to this confusion?

Thanks in advance to anyone that can help.