Discovery won't cancel credit card for pensioner

My pensioner mother has had the most horrific experience cancelling her Discovery credit card. She sent the cancellation form on 10 Sept and her card is fully paid-up, waiting to be cancelled. Today they deducted R105 for the card protector and Gershwin (ref ********** 482) told her that they won't close the card until she pays the R105. There was no activity on her card from 11 Sept (discovery fees and charges) to 17 Sept and again from 17 Sept to 1 Oct (more than the 3 days of inactivity they demanded before they would cancel the card). This multi-billion rand corporation is *****ing food from the mouth of a pensioner on a social grant. It's disgraceful.