Shocking protocols

I took out a contract in March , Made for me L . I contacted the call centre and advised I need to change the contract to SKY which is an even higher contract. They referred me to the store. In store I spoke to Mubanga Chansa who said this cant be done . I want to pay you more money , I dont want a new phone just increase my contract. It's crazy MTN doesnt want more money .... it's ridiculous actually. I dont want to cancel the contract I want to make it even bigger.... what a joke MTN