Rain harasses me and says I owe them, I don't know for what

Good day

I'm being harassed by Rain on a daily basis. They're trying to debit my account, claiming I owe them. My debit order would go off on the 25th of the month, however, on February, it went off on the 26th.

On the 27th, my internet stopped working and I assumed it was a network issue. I reached out to Rain and the assistant tried to troubleshoot with us, it still didn't work. He then said I may need to get a different router delivered to me.

I waited until the 5th of March and when I didn't get anything, I called them again. I have all the ref numbers of these interactions. They told me stories and tried to convince me to rather upgrade the plan I was on, I refused.

I called again on the 12th, still no internet. I decided to cancel my subscription and requested my refund, but I was told the February payment was for the internet I used in February.

They collected their router and ever since then, they've been attempting to debit my account. Luckily I blocked them. And now they keep calling me, saying I owe them. I have asked them what it is I owe because I had no internet from the 27th of February right until I canceled. What is it I'm supposed to be paying for?

Their calls are frustrating because I explain the same thing over and over.

Please stop harassing me. And if you mess up with my credit score due to your incompetence, I will have to find ways to escalate it to the relevant authorities.