Store refuse to refund me

I am highly disappointed with debonairs pizza rustenburg square, I place an order Monday via Mrd and the app gave me problem and the order ended up processed via collection and I call the store immediately to cancel the order and ask for refund and the and also call Mrd I was told to come in store and I explained to them that i am working during the week I can only come on Saturday and when I arrived there Saturday day refund the manager was rude telling me that is not the store false I should contact mrd, I ask the manager to assist me contact Mrd because I spent to much money on airtime call both Mrd and the store to let them know about my incident and I also bolt to come in store hoping that I can be assist and he told me that I want to waste the company airtime with the mistake I did,I am highly disappointed and they ended up call Mrd and Mrd says there is nothing they can do because the pay the store their money and the store is the one that should refund me and I wake out of the store without any help if after I showed the my slip from my email I have lost hope and I don't appreciate the service I received from that store and made me no longer want nothing to do with deboniars pizza