Negligence towards my order

My mom experienced the worst service from Timbercity, on the 1st April 2021, she went to purchase a garage door, of 4.1 meters.... around the 9th my mother starting calling the shop cause they said the door will be delivered soon...., the front desk staff kept on telling my mom she will be contacted back. On the 15th of April, my mom decided to go to the shop, only to find out that Elsie had taken the payment but never placed the order as she should have. So on the 15th of April 2021 it was a total new story to the lady who is busy charge with the garage doors. Last week Thursday they came and delivered a wrong sized door, and blamed it on my mother... yet she had given them the correct size but due to negligence and not caring the Elsie lady lost and forgot just like she had forgotten to place the order. They charged my mom R17000 for a wrong sized garage door but now they refuse to give her a refund for the right sized door. Please assist