84 year old forced to pay for handlagguage

My mother of 84 years old received her booking from Lanseria airport to King Shaka via email stating that she could take 7kg handlagguage. When she checked in today 14 May the lady told her she needed to pay R350 extra because she had a small bag from recycled material (like the woolies bags) with her pills in it plus a small carry on bag. The lady refused to weigh the two bags together and said my mother cannot check in if she does not pay. My brother paid for her but this is absolutely scandalous. The porter that handled her wheelchair at King Shaka also said that they have ripped her off, she was not supposed to pay.

Many people flew with her with much bigger handlagguage.

Now the question is, will we experience the same from King Shaka to Lanseria in a week's time?

She flew in February with the same luggage from OR Thambo and did not have any issues so why was it an issue this time around.