Horrible customer service, refusing to refund me

I bought a bag from yokico at mall of Africa , when I took it back for an exchange because the trolley is faulty, I was told to go to another branch, why? It make no sense cause I bought from them, can't they communicate with that branch so that it can be brought this side? I am very upset, considering that tomorrow my son is going to school without a bag, I do not have extra cash to pay for another bag and they refused to refund me