Responsible for own Courier and cost to return faulty camera

I bought a WIFI camera that was not working properly and the footage quality is poor. I told One Deal a Day that I want to return the camera for a refund. They said I will be responsible to use my own courier and will be liable for the courier fees as well. They also could not confirm if I will receive a refund or a voucher to buy something else from them. I told them that I do not think it is fair that I am responsible for the courier fees if they sent me a faulty item. They did not even respond to that comment I made. I then asked if I will still be responsible for the courier fees if I accept another camera that is working. I did not get an answer on that too. There services are very good when you order but their after sales are very poor. I am now sitting with a camera that is not working and are I am not prepared to pay for the courier cost since it is no my fault that they sent me a faulty camera and this means I am paying more for the camera at the end, which does not make it a good deal as I thought it was.