Gas heater not working

I made an online purchase on the 21st of June 2020. I bought a Salton gas heater, received a call last week informing me that the Salton gas heater is out of stock and I will be given another brand and the difference will be refunded into my account. I have received the difference, however the gas heater it is not working. So frustrated as I didn't get what I was supposed to get in the first place . Inconvenience at its best shame.