17 R5, adaptor gets disconnect to computer

Three weeks ago I sent my computer to Dell tech center to repair. The fan was malfunctioning. It had a large noice starting right from when I open the computer and it never stops. It got my computer very slow. After they sent it back to me, I realized they changed a part of my AC adaptor. I know that because there was white paint on both parts of the chord and there' s only one of them that I recognize. Then when I play large games on this computer, my battery drops from 100% to 95% when the AC adaptor is plugged in. The signal light was on and shown on my computer but it was just using my battery and not charging, About half an hour later, the AC adaptor will disconnect and my computer will lag hard. During my first call to them, they did all the tests and found nothing wrong with it. They updated my system and told me to examine it for one day. The problem was still there so I called again the next day. During remote control, the technician got my computer blue screen and cannot be opened. Then they requested to send me a flash drive to reinstall my system. After I reinstalled the system, the same problem occurred. I got the call back today and this time the technician told me they found an article online stating this issue as a NORMAL case that happen to almost ALL Alienwares. However, my problem was that it does not only drop my battery but my charger eventually does not function anymore.

 

This problem did NOT happen before when I send the computer to the technical team to repair, I think I have reason to suspect that the technician messed up with the repairing process and made this problem to occur. The technician during the last call states that there is nothing else they can do.

 

I asked them to send me a brand new ac adaptor, the same problem remain. Now I can only play games like DBD or Red Dead Redemption for 30 minutes at most. Then I have to replug it in and wait for it to recharge back up to play. This gets me really frustrated because I did not have this problem before I send it to repair and the whole process took so long. I am not sure what is going on and if there is a possible solution to it because the entire Dell tech team said it is how it is designed as mentioned in the article. Please help! I only bought this computer for less than two years and I kept it well. I do not want it to just become a piece of garbage...