Cellphone exchange

I bought a cellphone at ok furniture in vereeniging Mark Park on Friday 10/09/2021 the lady assisting me didn't explain that the phone was Simlock now went to the store to ask them to exchange the phone the manager Hendriette told me she doesn't want that phone back because is registers on my name ... We called Area manager John he also refuse to take it back all I want is to exchange a phone so that I could get the one where I'll be able to use a different Sim card