Credit Limit Decreased

I am really disappointed in what happened this month with my Mr Price account. I have paid on time every month since my account was opened. This month (September 2017) I was really busy and could only get to the shop to pay my account by the 9th of September 2017. When I paid my account the statement showed I have a zero credit available to buy and my limit has also been decreased. THIS IS RIDICULOUS AS I WAS ONLY TWO DAYS LATE.??????????