FED UP WITH RAIN

Can someone please explain to me why Rain insist on sending me sms and emails regarding arrears on an account when in fact I stopped using their services months ago and I have not signed any contractual agreement with them I am becoming very irritated with their stupidity your company is a month to month prepaid internet subscription if I don't pay I don't get to use the service its almost 5 or 6 months from not using that sim card I have even thrown it away.

This is ridiculous.