How do replacements work? Would an external antenna help me?

I'm getting a crappy signal where I go in Florida for the winter. I swore last year the signal was great down here, so not sure what happened. I want to try the external antenna route, but T-Force is saying they only replace it with the same exact model. I currently have the Sagecom FAST5688W. Seems so weird they don't give them the option to upgrade customers if they're having signal issues. I would rather ditch Spectrum for TMHI if possible, but I would like to try to get at least 100 down. If I go next to the n41 towers out on US-27 (Four Corners FL) I get great speeds, which is such a rarity for this part of Florida (both AT&T and Verizon suffer greatly compared to T-Mobile, I have/had both companies).

How are people getting the G4 models? Does it look like I would benefit from an external antenna like the Waveform QuadMini? T-Force is sending me a replacement in the mail, so will see what happens by the end of the week. TIA!