Insufficient prepaid balance in a contract phone

MTN do you want to loose me as a client together with 4 other contracts after more than 20 years? I have been a contract user since day one and enjoyed full value for what I paid for as a contract customer. Lately I cannot even send a MMS because it says I have insufficient prepaid balance. I am not a prepaid customer why treat me like one. Why must I load prepaid money on my contract phone if I use the MMS functionality once in a blue-moon. I use to have full MMS functionality why change the contracts now. Even this morning I wanted to activate an Openview decoder and when I dailed the ussd code I could not answer the questions because of insufficient prepaid balance.