Hi there,
I checked and your site is a simple one, though I can’t confirm or verify why it’s too large. I can’t tell if it’s a scam, but seeing that it’s a simple site with just translations then it shouldn’t that expensive.
You can try Blogvault services and backup your site, it will skip unnecessary files and junks then you’ll get the real size of your site. Then migrate that site to another host (staging) to get the cleaned copy from BlogVault.
About the issues, I can’t really tell. Only developers could completely examine it.
Thanks!