I didn't say DEMAND, nor did I mean to imply that.WTH? Last time I check there was not a universal right to demand a dual band router.
A tech company offers you adequate working device. Why should they replace your router for free just because your earbuds? reality distortion field .oO?
Just explain that you live in an area with a gazillion 2.4 GHz WiFi networks, and that you can hardly use your WiFi as a result, and ASK them if you can swap your present router for a Dual-Band model. They should understand. Really. Most people are generally reasonable, if you don't start out like a jerk.
When I moved into my neighborhood 20 years ago, I was the only WiFi network that I could "see". But around 10 years ago, that all changed, and it seemed almost overnight!
If I didn't have a dual-band router, I basically couldn't use WiFi at home AT ALL.
It's a common problem. Your cable company should understand, and most likely will. There are only like 3 "groups" of Channels on 2.4 GHz (yes there are 11 chans., but the way they overlap in frequencies, it works out to really only 3 "sets" of channels), and there are more like 150 Channels on 5 GHz. There's simply no comparison.