Poor service with phone

Good day, I recently bought a mobicel Rio phone from Ackerman's store in Centurion Mall on 07/12/2020 ,was assited by Thapelo and the phone is not properly working when I returned it back to the Store today 09/12/2020 I was referred to a lady named Sannet ,i told her the problem with the phone and i wanted to be refunded back my money so that I can buy New proper one when i get paid she said they only exchange phones and won't refund me back my money , Why customers forced to take products that are not properly working ....i mean it's only 3days that I have the phone please help me this is not right....my number is ***