Debiting when their product doesn't even work

Telkom was been de*****ing my mother with a plan that doesn't even work in her area since they stopped roaming on other towers. Everytime someone says that they will call her back but they never call her. A technician told her that he will be able to cancel the plan before it begins but he didn't and now they debit her for something she will most probably never use. Please assist her with this as its not fair. case number : ***0