Summer mobile and MTN

Mtn and summer mobile don't hold accountability I received a call in which they told me about a phone contract upgrade I told them that I want to finish my old contract I don't want a upgrade told the agent this only to find out the contract is upgraded without my permission on top of that I go to mtn to tell them they review said I must contact summer mobile they take long to reply like I don't know what's going on but if this continues I will open a case this is ******** actions