I have sent an email to settle the account they say I am owing more that doesnt refelect on my account

Hello Peter

I was settling my account with woolworths according to their online statement that they update every month , I paid the whole amount and they even sent me the sms to confirm that my credit card is up to date.

I sent them an email to settle my account guess what? they sent me an email saying I owe them R137.18, which is not on the statement but on the email that this lady si sending Lammes Cozen is her name. How did she come up with this amount she doesnt even bother expalining and she gives me an ultimatum of 5 days to settle ony then my account will be closed. Why do I need to pay amount thats not on my statement, Does this mean they charge us for settling accounts? If yes was is explained to me. She doesn't even bother humouring me by explaining on the email or calling.

What value added service is this?