MTN contract cancellation

I have been trying to get hold of MTN to cancel my contract since last month but as soon as someone answers the line goes quiet. This has been happening everyday for almost 3 weeks this is not on. I dont want to keep paying monthly for this but they are doing this on purpose so that i can keep paying. Its very frustrating someone answered and after saying their name the line went quiet and its been quiet for 30 minutes now. I dont know what kind of service is this.