Woolworth store account

Financial advisers will always ask if you have a Woolworths card, then tell you to settle and close it immediately. Now i really understand why. Even though they advertise 55 days interest free, that is not the case. I settled my a/c on 31.12.2017, made 2 purchases on 31.12.17 + 15.01.18. Then made 2 payments on 01.02.18 + 19.02.18, which left me with a nil balance after a total of 50 days. Yet they still charged me interest of R 8.06 + R 14.31 . The mind boggles just thinking how they are *********** people who have large outstanding balances every month.