Vodacom - Debt Review - Upgrade

I have been a client with Vodacom for years, But as luck would have it and circumstances I am now under debt review, yet Vodacom is not part of the debt review - I have placed it as one of my monthly debit orders which I pay monthly without fail. According to the debt review companies if you have placed it (your cell phone account) on your monthly expenses when you app**** for debt review, and you have proven that you can pay the account, then you are allowed to upgrade your contract, you are only not allowed to open a new contract. The query which I have been trying to sort out is, why would they allow me to upgrade my contract to a ridiculously high contract instead of a contract which is much lower and falls within my budget and terms of my debt review. I know what I can afford and what not.... Please explain to me why would you allow a contract so high but not affordable. My payment history with Vodacom has always been impeccable.