Harrashment from Call Centre after contract has been paid

After terminating my contract and the last debit order was successful end September 2017, i keep receiving calls and emails confirming that i still owe them money. I requested an email from Glocell to confirm that my account is settled and not owing. On 24 November 2017 i forwarded that email to Glocell and nimble group. After that email i still received calls and emails. TODAY 24 January 2017 i received an email Section 129 AFTER THE ACCOUNT WAS SETTLED. i spoke to Maserame Shabalala and on her system it shows the query has been resolved and paid.