Usage spikes as hack attempts are thwarted

I’m an amateur and hope someone with more experience can shed some light on what’s been going on lately. My site has been subject to multiple hack attempts over the last couple of months — escalating in the last couple of weeks. While WordFence seems to be doing its job at fending them off, the bandwidth usage spikes out of control every time this happens, with the result that my site is down for a good part of every day now — and it loads slowly even when it’s up. My plan’s usage limits have always been more than adequate to handle normal traffic to my (primarily text-based, non-video) site.

The company that hosts my site says they’ve received many similar complaints from other customers over the last few weeks but they have no fix – other than to suggest I pay them for a VPS.

1st question: Is this a widespread problem or might it reflect an issue with my host’s servers? In other words, should I consider switching host companies? 2nd question: Why does an attack that’s been successfully deflected pull so many resources as to overwhelm the site — and is there anything my host or my web designer can do about this?

Thanks for any help you can offer — or even for links to discussions of what’s been happening recently.