BAD BAD SERVICE

I bought a phone at Ackermans on 6 August 2022. It was a Saturday. However when I came home, I realized that it had no network coverage which meant I could not access the internet or use the phone while at home. I returned the phone Monday 8 August 2022 in its original packaging with all the accessories inside the box for a refund as this phone does not serve its purpose due to no network. I was told to leave the phone there and to wait for an email from their Head Office. Today is 15 August and still no answer. I contacted the manager who was in Beaufort West, only to be informed that I cannot be refunded, I have to collect the phone and keep it as I had already bought it. How can they take my money and refuse a refund if I'm not happy with it??? So if you shop at Ackermans you are not allowed to change your mind?