Woolworths harassing clients about arrear accounts before due date stated on account

I have had an account with Woolworths for more than 15 years. From last week I keep getting phone calls from them telling me my account is in arrears, even though the due due date on my last statement is 4 February 2019. I paid my account on Saturday 2 February and low and behold today 4 February I get a call again from a very aggressive woman.

NEVER once was my account instalment NOT paid in all the years.

I even paid more than I was supposed to this month.

If this is how Woolworths is treating their loyal customers, they are going to be losing many.