No feedback from Manager

App**** for a credit limit increase a month ago. I requested a lower amount than what I was pre-approved for. For some unknown reason it was declined. I called the credit department a few times, who could not provide me with any information to why it was declined. Thereafter I called the Credit Bureau, only to find a good credit review. I have escalated the query with FNB four times till date, with no feedback or response from management. I have been a loyal customer for 17 years and this is the kind of bad attitude I receive from management???