I need help with my wireless problem. It isn't working upstairs. How do I make it work?

I have talktalk broadband. I have the HUAWEI router. It's currently on channel 09 as advised by talktalk. I have a cordless phone which I cannot get rid of. Sometimes I see my wireless in the available wireless window, it has excellent strength supposedly; however when I try to connect it won't connect. This is driving me crazy. I tried to call talktalk however it was an unhelpful call centre and would not talk to me as I was not the bill payer. What can I do?