ABSA Finance Charges at 380%

On the 3rd March R21333.89 was taken **********ly from my credit card account (online)<br> On the 9th March ABSA recovered and refunded R17343.20<br> On the 11th March ABSA reversed the recovery by debiting R17263.85<br> On the 23rd March ***** recoveries deposited R17343.20 once more<br> <br> End of March total balance on my Credit card was approximately R5400<br> On the 6th April Finance Charges added to my account amounted to R20725.68<br> Statement shows Bank charges - \Interest rate per annum 17% \"<br> Mathematically 20725.68 is about 380% of 5400 (not to mention \"annually\" should be apportioned to 1 month)<br> If not mathematics - what kind of calculations is ABSA using on my account? Chemical, Science Fiction or <br> Who Wants to be a Millionaire ?"