Awaiting credit note since 25/7/18

I have been waiting for a credit note from 25/7/18 and as yet i have not received it. After numerous calls, e-mails, I finally received a reference number on the 31/7/18 from the debtors e-mail account. Since then all is quiet. I have called customer services citing ref. no. and been told to call the switchboard and ask for accounts but there is no answer on the switchboard number. I am at my wits end as I need to resolve this. TNT you suck and cheaper rates or not, I will never ever refer your services to anyone.