Unauthorised charge

I cancelled my wifi service on 31 December, and I was told that I will still be billed for January due to the late cancellation, which is understandable. I was charged for January, and I was TOLD that I would not be billed again for Feb. I’ve been charged for Feb; and when speaking to customer service, they said “my cancellation is being reverted, and I need to cancel again” why must I cancel twice?? Now I paid for Feb, for a service I do not use?? I need to cancel again, just for them to charge me in March and say I must probably pay AGAIN. How is that okay??