Refusal of exchange due to a box and distasteful attitude of a staff member

Good day

I purchased a new milex Carbon Fibre heater, from Canal walk homemark store, on the 27th June, when operating the heater on level 4 for about 15 minutes it kicks out a "error code 1" other times the device just goes off completely, Today we tried to return it to the store as it's our 13th day, and the senior in the store Thea governor was really professional and accommodating, however Anwell Motumi the junior in the store was extremely arrogant and clearly subordinate his senior, very unprofessional, and according to Anwell Motumi the reason why the device is switching off is because we can only operate the device indoors at level 1 and 2, keeping in mind the device is advertised as a indoor/outdoor heater no where does it specify that you cannot use it at level 4 indoors, he further went and said it could be due to load shedding, I responded to him by saying we are using a surge protector plug, he the said that the room is to small and that's the reason for the device switches off due to the room being to warm, I then told him that the device is positioned in front of a 2.4m sliding door, opposite the sliding door is a 5m2 window in the room the room is about 40m2, I then asked him if he's a technician for the device and he said no, I ask him so what are you basing your information on and he couldn't answer,

I then requested that they replace the unit, they refused as I don't have the original box, I said fine give me a replacement unit and then keep the box again the senior was keen on this the junior member was not.

I requested that they rather refund my money, they again refused due to the box, I said fine deduct the boxes amount and refund the rest of the money, they couldn't accommodate me.

I then asked them if I could take something else to the value of the device they refused.

I'm honestly disgusted in your par of after purchase service, it's a distasteful and disgraceful attitude that some of your staff has.