Bad service

I have settled my loan on 20 June 2015. I have settled it in full as per the settlement letter provided to me, which was valid until 23 June 2015. My instalment for the month of June was still debited as my account had already gone into tracking by the time I paid the settlement. I called and spoke to Vadette who confirmed that the refund was due. When after 10 working days the funds did not reflect in my account I called into the call centre again and was very rudely told that I was not due a refund as I paid my settlement on 23 June, whereby the settlement letter was no longer valid and further interest has been charged. As per my loan statement the settlement was only app**** on 23 June, which is in any case irrelevant because even if I did make the payment only on the 23rd it was still within the validation period. The settlement letter states that the letter is valid UNTIL... UNTIL means that that same day is included. As I'm lodging this complaint, I'm also lodging it with the NCR. I will also be re - posting it on your Facebook page. I have had enough of your call centre staff talking over me and being impatient when all I want is to no longer be associated with FNB!