How To Change Router Frequency

I have been having a lot of problems with my turtle beach transmitter blocking any wireless signal coming into my room, which is really odd, anyway after a few messages to the company, they have told me to changed my router frequency from 5ghz to 2.4ghz and that should solve the problem.Now I have sky Fibre, and have one of the Sagem N routers provided by sky.I have gone into the router settings and I cannot find anywhere to change a frequency.I thought the router would have been n a 2.4ghz frequency anyway