@Dario258 Well, if a host lists something, like unlimited Internet, they should provide that without an extra fee. That said, she may have a situation where she lives like I do, for which there is no appropriate box to check on the Airbnb platform. My internet is cell-based and metered. But there is no place to indicate that, so I had to check Wifi: unlimited as none of the other Wifi options applied either. But I make it very clear in my listing text that it is, in fact, metered, and that guests are limited in what they can do online-no streaming, netflix, downloading or uploading large files. All my guests have been okay with that, if they need more, there are cafes in town where they can hook up to free unlimited. The couple of guests who were online a good portion of the day did use up a lot of my data, but it balanced out with the ones who hardly used it at all. If I had an pricey listing, I'd just make sure to pay for enough Wifi that guests could use as much as they need, but at $28/ night, I can't do that.
It's possible that this host hasn't ever had any other guest use anywhere near the GBs you are, and she wasn't prepared for that, but she should explain in her listing, like I do, that there are limits.
She may also be used to guests who are out and about most of the day, who turn the heat down when they're out, so that you're there a good part of the day working online with the heat on may also be why she is distressed about that.
However, the host's financial situation, her debts, etc. are none of your affair, and when you rent a place, you certainly have the right to be comfortable, not cold.
If this host is someone you feel you can talk to, I'd sit down with her and explain that if she lists unlimited Wifi, that's what guests expect, without having to pay more and that heat in a listing when it's cold out is a given. Perhaps you could offer her a bit for the Wifi, if you feel like it and think that's fair. I think Airbnb works best when hosts and guests are willing to cut each other a bit of slack and be somewhat understanding.
You could take a hard line and call Airbnb about it, or you could cancel the rest of your booking and look for another place. If she's insistent on you paying the amount she said, you might want to do that.