Unprofessional and poor customer service

My mom did a laybye at Russells (sun village). Upon the last payment she was told that the sound system she laybyed is out of stock. And she needs to pay R400 for it to be delivered from rustenburg branch.

Who's responsibility is it to make sure they have stock?? Why is it her responsibility to get the sound system from rustenburg when she didnt laybye from there? It was a horrible and unprofessional experience that me n my family and friends will never set our foot at Russells again.