dell wont return my computer

I purchased my computer at the very end of 2018, on 24/12/18.  When the computer first arrived there were a multitude of issues. it kept crashing over and over, I kept getting blue screen errors, the computer would get really hot, the fan was super hot, etc. I wanted to return the computer, but my dad said we should try and resolve the issues instead. We were constantly wasting our time on the phone to dell, updating drivers and windows and so on. Dell kept telling us that the computer was fine because nothing showed up in the diagnostics, when that was certainly not the case. after some time of trying to fix it we came outside the 30 day return period. After wasting what I would estimate to be at least 9 hours of phone calls and updates, dell said they would send a technician over. He replaced a ton of the hardware in the computer. after he left and I logged on, I could not connect to the WiFi, resulting in another hour long phone call with dell to resolve the issue. It has now been a few weeks since the technician came and i am suffering from a ton of the same problems. I am a 16 year old kid from Australia, and i wasted a good portion of my life savings ($2,700) on this computer that hardly works. I still have the original packaging that the computer came in, and the computer is completely undamaged. I would be so thankful if someone could suggest a way for me to get my money back.