CHARGED INTEREST,DESPITE BEING GIVEN ASSURANCES TO THE CONTRARY!

For the first time ever,it completely slipped my mind to pay my credit card account by the due date. The moment I remembered,I immediately paid the full closing statement balance,as I always do. I then immediately phoned FNB. I was put through to the "Collections Department". Although I do not have the name of the lady that took my call,since all calls are recorded,there has to be a record of my call somewhere. She assured me IN NO UNCERTAIN TERMS,that I would NOT BE CHARGED ANY INTEREST,due to a "Grace Period". She also said that she would be making a note of my call to inform FNB of my payment. Imagine my shock when,despite the assurances I was given over the phone by the Collections Department,I WAS charged a hefty sum in interest,regardless. In over a decade that I have been banking with FNB,I have maintained my Account perfectly. The one & only time something like this happens,despite clearly being told otherwise,I am yet charged this outrageous sum in interest anyway. In my experience,other banks have been so much more accommodating when it comes to issues like this. Needless to say,once I pay off my credit card,I will be taking my business elsewhere!