Russells Refuse to Refund nor give me a new Microwave

Bought a microwave at Russells cash, when I got home to test the microwave to my surprise it wasn't working, returned the microwave but they refused to give me another 1 nor refund. It's been 3 weeks now I haven't head anything from them. I tried calling them they just said they will call me. Till today they haven't. I'm not happy at all about their service. Now I'm stuck without a microwave. I'm sick I can't stand of the stove to cook, They bring me food as I'm staying alone I just have to warm them up. But now I have to eat cold food while I have a fully paid microwave out there.