Destroying my device without my knoledge

I sent my device to mtn repairs and when I was about to make payment I called to find out what must I use as reference only to be told my phone has been destroyed and no one at mtn shop can assist they all don't know what's going on and now I'm paying for a contract for phone that's no longer there I wasn't notified about anything they just destroyed phone without even telling the mtn shop I sent phone to or contacting me