Nokia C20 died after 2 of use

I am utterly disappointed with Ackermans cellular. I bought a Nokia C20 cellphone on 17 June 2023. Within two weeks of using the phone, it stopped working. I took it back and they indicated that it had a system error. They are claiming that they fixed it but I am concerned that it will stop working again. I am asking Ackermans to give me a new phone but they are refusing. This is because they sold me phone that had system error and I am not happy. Rather they refund me or give me an alternative phone.