I have sent them the mails and they say they will investigate, by tomorrow I get another sms again or my wife gets a sms

I cancelled my wi-fi subscription about 2 years ago and got a confirmation back from Rain that they did receive it, I am now getting harassed daily by Rain and a company Nudebt and threatened for being arrears and have to pay the amount into their ABSA account "Final Notice of Action" I am fed up with this any suggestions please