Unfair Treatment

Good Day

I bought a Lenovo laptop and printer for my work 4 months ago by this shop, so now the laptop and printer is faulty. I took it back last Friday now they dont want to refund my money or give me another laptop, they say I must wait for 3 weeks they are sending it for repairs but they dont understand I have to work and dont have a spair Laptop. Whole I was there busy with them another customer came with a faulty printer and demanded his money back and they give it to him but whh musg I be treated unfairly. Bad service because I am stressing about my work pilling up. Thank you