Payment reflection understated and incorrect balance

I got my may statement. Outstanding balance was 8450. Made an eft payment of 8300. To my surprise when i went to check if the payment was reflecting gota shock of my life as i now has a balance of just over 800 andi do not recall purchasing anything before the payment or even after i had recieved the May statement. Called woollies customer care held on for ages only to be told the agent will enquire on my behalfand she took long toget back. Till today that balance hasnt been resolved. Woolworths do the correct math and fix this as i wont pay an exta 700 for nothing. Is this how you rob your customers?????