Need a solution urgently!!

I bought a new cellphone ( Netsurfer) cash last year on 03/06/2018. 9 months later the phone started to give me problems. I took the phone back to the Fairbridge mall branch in Brackenfell, Cape Town where I bought it. There we realised that the battery was finished. It was swolen. The cashier told me that it will take 3 to 4 weeks for the phone to come back from repairs. I think it is ridiculous. It is only the battery thats faulty. I urgently need a phone because I need it for my job. I am waiting already a month now. RESOLUTION: Refund me so that I can buy me another phone somewhere else. I am also a dedicated customer to you and even have an account with you for many years now. I didn't know that I will be dissappointed in one of your products. I want a manager to contact me and tell me what the resolution will be.