Being treated unfairly and poor customer service

On the 8th of April I bought an Alva gas heater at Builders Warehouse after a couple of days from date of purchaser the heater was defective and it could not switch on I then took back the heater at store it was tested and the gentleman who tested the heater said it is working they will not exchange/refund the heater if it is working I then took it home and it only worked for few days. I took it back again on the 12/04/2022 and it was tested and could not switch on it was then replaced. I took the heater home it worked for a week and then took back again to the store it was tested again and the gentleman who tested the heater said there is wire that was loose he fixed it then the heater switch on. The heater only worked for days then it stated with the same issue again it could not switch on. I then decided to take it back to the store the 4th time it was tested again an the gentleman said there was wire that was loose he cut the wire. I advised the lady at the reception Patience Raloane that I would like to get the refund as the heaters are defective and I cannot always bring them to the store to function for week I do not trust the appliance anymore. I was advised that the heater must be taken for repairs the period for me to get a refund has lapsed however whenever I return the heater I was told that they cannot a replace a heater that is working. I am lodging against Builders warehouse for refusing to refund the my money back and insisted that the heater must be sent for repairs for 21 days and I must be inconvenienced without heater throughout the winter season and despite several attempts of returning their defective heater. I wish to express my dissatisfaction with the poor service Builders and request any form of intervention to stop Builders from treating me unfairly and withholding my refund. I spoke to Mr Molepo who I was not happy with the way he handled my dispute and when asked where can lodge my complaint he then rep**** with an attitude and said that I must go to the builders warehouse website I am within my rights to complain. When I returned the heater the first time I was not offered the option to request a refund as they cannot replace a heater that is working and the heater was defective within the first week of purchaser I am now told that I cannot get a refund as a month has lapsed.