Cell C is too bad guys becareful

In 2018 i did an upgrade with Cell C i told them i dont want to change my package but they changed it without my authority by giving me a handset that they were getting rid of it,that handset its only at Cell C,no parts for it. And also tried to bribe me with 500 minutes for changing my contract package of which i rejected.

Now the handset has a lcd problem it just got blank,i sent it to repairs at Cell C,i got a call from repairs telling me that thet dont have spares for my phone i have to pay R2800 for them to give me a new phone because they cant fix my phone that they gave me.

My question is

Why did they gave me a phone that they new it wont last two years and they wont have spares? Who gave them authority to change my contract package? Why do i have to continue paying the contract that i am not happy about it?

What do i use from now on until the upgrade date of October? I have tried to call Cell C several times no one is willing to help me.