I feel discriminated against by vodacom

I have been a loyal customer to vodacom from school days, for the past 4 years i have got 2 cellphone contracts under my name, i went under debt review about a year ago but continued to pay my vodacom every month without fail, when going under debt review i made a note of my cellphone contracts and they were taken into account with my affordability.. now i want to upgrade with a plan that cost the exact same amount a month but I am unable to, it is very upsetting because i am not getting a new contract i am upgrading a current one and will b paying the same premium every month as i have always been paying. why cant i upgrade?