Cellphone contract upgrade refused

I have had cellphone contracts with cell c for over 5 years. I went under debt review last year, but I'm still paying for my 3 contracts with cell c. I am now due for an upgrade on 1 of my contracts in April and Cellc is refusing to give me a new phone. I am very disappointed as I am now without a proper phone and I have been paying my accounts for the past month without any problems