55 days interest free on credit card - what a **** (not even 30 days from statement to statement)

Good day

As I've had previous bad experiences with FNB's credit card department so I just had to put this on HelloPeter this time.

So this month I received my March's Credit Card statement, to my surprise I see that it doesn't add up to my excel sheet of credit card expenses I keep. I check it again, I see that there is interest on my account. I keep an excel for the reason that I can see what my previous month's balance is and pay that before the end of the next month so that I don't get charged interest. I've paid Feb's closing balance before the end of March, that means, I've paid the total owed in 31 days, but I get charged R168.81 interest (on a +-R5000 balance, which was paid on the 5th, 18th, 25th and 30th of March). Annual interest rate is 22% or something (can't even get it on FNB's website or on my statement), so if you take R5000 * 22% * 1/12, you get R91.67 (I get charged R168.81). I logged a query last Monday (8 April, 09h14) after I received my statement and reconciled it to my own calculations, I only get a reply yesterday (a WEEK later) and the reply didn't give proper explanation how the interest was calculated or on what balance exactly, just my Feb balance was paid on this date and that was the only reason given....

January 2017 I switched to FNB from Standard Bank just because Ebucks was better than Ucounts at that moment. From January 2017 I've had so much problems with FNB, the hours I've spent trying to get my accounts sorted (my residential address is STILL wrong on my credit card statement after I've done it 3 or 4 times at the branch), I've asked for the recording of my original phone call with FNB in January 2017 I don't know how many times (still haven't received it), the support structure from FNB is shocking, takes more than 5 working days to get back to a client regarding a credit card query (really?!!!) and ofcourse the whole thing about 55 days interest free, definitely one the biggest lies (inaccurate advertising) in the industry.