I'm not happy at all

Hello Peter it's my second time I'm writing to you I've complained about the stuff that I've bought so they came to exchange but they didn't install my bedroom suite and I told them I won't pay until they fixed it so 2 weeks back they came and installed it so I told them I will start paying this month end I was supriced to see them at my work dimanding that I pay I was explaining to them that I will come on weekend to pay, I feel like they making this my fault that Im not paying but I'm not paying because I was not happy and I didn't like the way they behave in front of my co-workers i need them to come and take their stuff I don't want anything to do with them anymore