Russel Hobbs Microwave

Good day

I bought a new microwave and a fridge at OK Furniture, Attlyn Atteridgeville in May 2019. The appliances started giving me problems earlier this year, because of the lockdown I couldn't go report them at the store. I only reported them in May 2020. The fridge had a problem of over freezing. The rubber was loose thus allowing air inside the fridge even when closed. The microwave had a problem of automatically operating on its own. The store then replaced the appliances, end of June 2020. The same microwave that was replaced is giving me the same problem, operating on its own. I'm really worried about this. Even if the wall plug is on the microwave isn't supposed to start warming up by its self without anyone touching it. Was the microwave really fixed? or it was just repackage as is, then set back to me? Cause clearly I can't experience the same problem over and over again. Or perhaps it's a factory problem from Russel Hobbs? This is a serious matter cause that microwave can cause an explosion. Cause when it starts operating by itself there's nothing inside.