Rude Manager at MacGregors Clothing Store at Birch Acres Mall

On Friday the 23rd October 2020, my son (12 years) took the money at that didn't belong him. We went to MacGregors Clothing Store in Birch Acres Mall. He bought at T-shirt that cost R799.99, he knew what he did was wrong because he disposed the receipt. Yesterday, I went to shop wanting to return the t-shirt, the manager at the shop Mr Hosea Mbambo, refused to assisted me, he even told me that I should come with the police before they could me. He told me that my son 12 years old is an adult and he knew what he was doing when he took the money at home, he went to tell me that they have sold items to kids that are as young at 8 years, who have also took money at home. Mr Hosea Mbambo attitude was very rude and unkind. All I want to return that expensive t-shirt and get my money back. Should I then involve the police, simply to return an item?

Birch Acres Mall, Festival Mall Johannesburg, South Africa. Call ***