Payment methods

Good day,<br> <br> I would like to find out how your payment plan works. Sometimes, I get a statement telling me I am overdue, even though i already paid. Sometimes, I have to pay double installments even though I am on the 6months plan. According to the call centre you have 6months for every purchase. Also, my cycle keeps changing, so it is never consistent to a fixed period. Every statement I get my monthly cycle has changed. How is the installments calculated? It is extremely annoying and just around me at work, there are 4 people with the same problem. How is your things calculated?? Once, I bought something, and I had to pay more than 80% of my balance by the next month. It makes no sense!!