Complete incompetence of Nu debt management

Despite the fact that I have sent the. E mails with proof of payment in June All I get is threatening letters and another ticket number telling me that they will come back to me.As yet I have had no response to a single E mail a knowledging my payment just ticket numbers assuring me if their best attention at all times and nothing is done I have nothing left to do except let them take legal action and then I will deal with the lawyers and show them my proof of payment I have never been treated to this inefficient and absolutely abominable lack of attention to sort out a simple payment made months ago and sort this matter out. Mrs Marilyn Dinner