Rain absurd service

Last year in June I was using Rain simcard for unlimited internet access which is a month to month subscription. However due to the poor network connectivity with the simcard I had decided to cancel their service and there were emails sent and calls made in that regard as evidence. Surprisingly today I received an sms stating that Rain has handed my account to Debt collectors. How so?, when I know I did not sign a contractual agreement with them. This is utter nonsense. Rain is very *********** and they are ******. Trying swindle customers. I am going to further escalate this matter as Rain had violated my consumer right.