Credit Card paid upfront, yet treated as bad payer

In December not only did i make a payment for the Nov month on the 01 Dec 2015, as i would be traveling in order to meet all my commitments i paid before departing all my accounts again on the 17 Dec 2015.<br> The only service provider to have a problem with a client paying upfront seems to be woolworths, not only have they sent me an sms stating i better settle the account but i can too loose my good credit standing, but they have gone ahead and charged me additional interest as if the payment was not made at all.<br> To make matters worse, after receiving this sms i immediately called the call centre on the 20 Jan 15, where they told me that is how the system works and they don't know if they can reverse and assist me. The lady escalated the call, however i received no e-mail. Additionally the next day i called again and spoke to Morne which told me i must make an additional payment in order to clear my name???? Am i understanding this correctly i paid in advance and yet have to pay more. My future behaviour naturally would be to delay payment only with woolworths as i get treated worse paying upfront. Talk about driving bad behaviour. Disgusted and i have been a good client for over 15y