Returning decice request

I had just received my modem by mail and tried connecting and I’ve been trying all day to get some help connecting and resetting, fighting the cables etc all the steps I’ve been told. It’s my first day receiving this modem and tried connecting and it won’t at all. And now I checked my account and now it says I’m to return the device by Oct 22 to avoid a $240 fee?? Why am I returning a device I barely received today that does not want to connect, yet on the app it says “connection looks good…..” and also why does my account have a $20 charge that needs to be paid by then as well. Literally just got the modem today and it’s not even working and before I even do more there’s already a returning charge going to happen??