Mr kammies

I would just like to know who deals with payment, because my debit dates keeps getting later and later, October was so late I didn't have funds so in November it went off twice, now I receive sms stating I am 4 months in arrears which is not on, I checked my statements now I am up to date, if I din t pay for a month it was paid double the next, and why did my payment increased if the interest rate came down in South Africa and this without notification I would like this cleared up soon.