Refusing to give my deposit

I moved in wonderpark Estate in North of Pretoria last year September with my ex "father of my kids" . He was not working and I was the one paying rent and settling electricity and water bill. And I'm the one who paid the deposit of electricity to be opened when you move in.

Things didn't go well between us that He had to move out and I myself I had financial problems I decided to move out of the bachelor to share a two bedroom apartment. I wrote a letter to amps Metres to let them know that I'm moving out so that they can close my account... When you move out normal you must get a deposit back from them after your bill is settled...

My problem is that they are refusing to give me deposit back Because they are saying we both signed the contract and which I understand that part but I was the person Who was buying that flat and bill every month and I have proof those of payments under my name, the worse part is that I don't know where is that guy I have months not talking to him and his not responsible for the deposit that I need to get it back from amps metres