Horrible service at Woolworths and overcharged

I have an account with Woolworths they always had charges which I know nothing about. Last month my Balance was R1900 then they said I must pay R116 for month of august I then pay R300 so that my balance would be R1600 so they sent me a statement to with 1700 balance and it shows that I paid R300 according to my knowledge my balance supposed to be 1600 . Woolworths since I opened the account with I had a bad experience firstly run arounds to get a card when i got the card was declined.