Unattended Query

I bought a Alva gas heater from Takealot and when I received the heater on the 9th of June 2020 when I assembled it I noticed that the heat adjustment button was broken. I then immidiately logged a self service return and I received an sms that it will be picked next day the 10th of June. It was not picked up as per the sms communication. I then called their call center number provided it was forever busy. Today I called the call center 15th June there is an automated voice message that says lines have been deactivated. How do we then deal with our queries when they are unreachable. Their service is bad and I've been a loyal customer for the past 4 years. I bought that heater before it got cold and I have small children In the house and in this cold weather and I thought they would collect and exchange as requested