Vodacom Cash Phone

I am a loyal Vodacom customer for at least 15 years. I have several contracts with them. 3 weeks ago I bought a Samsung galaxy A03 cash for my friends son, who's phone was ****** at school. There was no mention that the phone is network locked. I wasnt even aware that network lock is still allowed so I gave him the phone as a gift as they need the thing for school. He did a sim swop and when he put his simcard in the phone it displayed a message "network locked". Now I am told that the phone can only be removed from the network after 12 months. 12 months for what???? He has a existing contract on another network that his mother is already paying for. I helped them because things are tough for everyone at the moment but now he has a phone that cant be used. This is absolutely absurd. I understand contract phones being locked but a cash one just doesnt make sense. Nobody can give me a explanation to why????????? I am really dissapointed.