Intermittent connections and choppy network is the game

They had quality service upon customer acquisition and delivered the modem promptly. Since the modem has arrived I've been having serious connection issues. I initially thought it was teething issues but after a week I complained about it the multiple disconnections and often nonworking channel(5ghz mostly). I kept on having issues and now the issue is clear that their modem has 3 metre radius range for internet and anything greater than that it doesn't work but you can see or pick up the wifi signal but it has no internet or network connection. They keep saying they don't see the problem and everything should be fine but I keep experience dropped connections and it is quite a terrible Service provider to use. I would not recommend it.