Woolworths Financial Services lack of service

I have paid my Woolies Card in December and in January but Woolworths financial services hasn't reflected them on my account, so i am being harassed daily by their debt collectors MDB. it has now affected my credit score. i have made payments using the same info for decades without hassle. i have been trying for weeks now to sort out. I have emailed my POPs around 5 times to different departments to get resolved without success. What do i do