tried to convince me saying I hadn't set it up correctly. After two days of struggle he agreed to take it back on condition if it was not found faulty I will have to bear the courier cost, which I accepted. He had the unit for two full days and kept telling me he didn't find the problem which I described to him. I asked him to try various combination - switch it off/on, leave it on/off for a while (in fact it never worked for me). He told he had done everything but the unit behaved as it should be. I wrote him step by step what I had tried at home and it failed to recognize, and asked him what was wrong in it. He replied me he cannot do any semantic checks(!) in my descriptions. (All our communications were via email so I have the records). Finally I agreed to take the unit back reluctantly. He even quoted me the courer cost and sought my confirmation to use the credit card detail I had give to him earlier. As soon as I had sent the confirmation he replied with apologies and confirmed the unit had "spectacularly" failed. He was so adamant all the time the unit was working perfectly alright. I got so frustrated and asked him more explanation but he never gave me one. I didn't understand the reason he behaved that way but now beginning to wonder it was because he didn't want to give