Refusing to give me a refund

They took so long to deliver my order then I made another plan Monday I phoned and told them to cancel the delivery that was still not even arranged. On Thursday I phoned again to tell them to cancel and refund then late afternoon, they delivered the stuff that I no longer want. I have asked that they come to pick up the stuff and give me a refund, but they say no because it was already delivered. they are refusing to refund me. I will take this to the full extent of the law. I want a full refund and nothing else will please me nothing.