Failure to deliver support to a loyal customer

I have been trying to get a paid up letter for a short term loan I took with FNB in 2014 and paid up in 2014.IFNB has been contacted a couple of times in the past three months to get this letter and still none response.I've eeven gone to their branch at Mall of The South where i was put on the phone for close to an hour with an agent who was trying to assist. She assure me the short them loan department would send me the letter in 48hrs, that was monday 04-09-2017 and today its thursday 07-09-2017. Still no letter!I am very upset with this lack of delivery from FNB as this letter is hugely affecting my credit record. If I dont get any letter from FNB I will close both my personal and business accounts with them. They clearly dont value their loyal customers. This is the email they sent me after my query monday "First National Bank:-) Reference number ********** Q has been issued for your query. To follow up with us you can contact ********** 937.4 Sep 16:37" however when i call this number it doesnt go through. Pure incompetence!