Harassment by Credidworx

Creditworx keep on contacting me about a debt handed over that I paid and settled in November 2016. I sent them the Proof of Payment and proof that the amount paid was to settle/cancel the account. The email was sent to ********** on 19 September 2017, however, no action taken as I still receive calls from different people who do not know the knowledge of my email. Today the 8th of December 2017 I received a call from creditworx made to my mother's phone by some rude lady saying it's my name that has been listed and I should be the one following why my account has been handed over. If that's the case why wasted my time and ask me to send them this email if they know they will not action on it? Such rudeness. Also, why is Creditworx not following up this account instead they keep on calling me non stop? These phone calls are considered an ******ion and harassment and I do not appreciate them. If they don't resolve the issue soon I am going to file a complaint with the Credit Ombudsman.