Ackermans Dont Care Selling gaulty samsung phonr

We are a household of 7 people. I buy all our phones from Thabo at Alberton City mall due to his friendly quick service. On 1 May i bought a Samsung phone. On 9 May the phone could not read any sim card. Thabo fixed the problem. On 10 May same problem. He was still busy placing card in the first holder phone went completely dead. Now it cant switch on. Nothing!!! Ackermans head office dont want to authorise to give a new phone or refund. I explained the phone is for someone with a serious MEDICAL condition. No mercy. I have went back to store. Nelson assisted. Store manager or in another branch or off. Numerous emails no reply. I bought a phone at Cash Crusaders and ask that i get refunded today. My budget dont allow for 2 phone sales a month so you are taking pur tramspirt and groceries money. Nelson and Thabo did everything they could but head office hides behind a phone. I need this matter resolved today