There are strict rules about what a Front Line Agent can and cannot do. Once they tell you they can't do something
"Can I please speak with a supervisor"
Try to trim down your explanation though, just say that the agent must have misunderstood you, and that you didn't request services being cancelled so you would like the charges removed.
Also this is a very important thing of dealing with Customer Support, be as concise as possible, and make them repeat what they are going to do. When things get too long and convoluted (as above) mistakes WILL happen, it may make sense to you, but your just one in 30 people they will be talking to today.
Didn't get to the bottom when you said it was resolved, congrats on getting it resolved. My advice still stands though