Upgrade access

I only have one seriouse concern. Why do one have to pay an certain amount when upgrade to a new hand set on 20 out of the 24 months. My feeling is that MTN is trying to get back money from its loyal custamers. If you as a client uograde to a new contract and get new handset then why must one pay the outstanding on your previous contract. It does not make sence. As many clients will drop them because of this. If you upgrade most of the time you pay more towards the contract than the previous contract.