Account paid up but still get calls from Attorneys

Horrible customer service - still waiting for paid-up letter and getting calls from different Attorneys I have settled my standard bank overdraft on my cheque account on 25 March 2020 through Daly offering 20% discount. I requested for the account to be closed and to be emailed a paid up letter on the 25 March 2020. On 27 May I got an SMS from MacRobert Attorneys saying my account is overdue, I called them to inform that the account is paid up and have been waiting for the paid up letter since March. Sameday I called Dally Attorneys to follow up and they advised that they are waiting on Standard to send the letter. I called standard bank on 27th May to request the paid up letter and to confirm if the account was closed. I was transferred to legal department and spoke to Bulelwa, she confirmed the payment settlement received on 25 March and she is actioning for the account to be closed and paid up letter will be sent within 7 days . only received the paid up letter stating the account is closed and paid up on 28 May 2020. I am still getting messages and calls from Macrobert Attorneys saying I have an overdue amount. Can standard explain as to why would I be having an overdue on a paid up and closed account. This is really frustrating and pathetic customer service