Bad Service - 3 years later

I used chubb +/- 3 years ago, i paid the account via debit order monthly, yes i can say that there was a month or two which i did not make payment but i ensured that i made them as soon as I had the funds available, as per continuous calls and sms i received i had to make sure i paid it, i moved out of the premises where it ws installed and called chubb and explained that I would like to cancel with them and they need to assist, a technician came out and removed some box and we were assured that it will be cancelled, to my surprise late 2017 i start receive calls that i will be handed over due to arrears wow 2 years later,this is a joke. i call and make enquiries and so forth and all i get is statements of months of account not being paid shocking- i ask for a recon and get statements no can assist, i still get these threatening sms of me being handed over and that my belongings will be attached imagine for a R1200 odd.. i call nudebt again and explain this story once again and the consultant explains to me what the procedure should have been upon cancelling, and that i should have received a confirmation thereof, she said she will request for a copy of contract- still i receive the sms old sms' threating me- i am really not happy about this and feel that i should not pay this as I am not liable for your faults..SORT OUT THIS MESS and stop SENDING SMS's