Not saying there are companies going above and beyond for customer service but getting a human answer at all when spending single-digit euros a month seems impressive enough; then again I am european so certainly biased :)
What would an american provider have done? Changed their pricing model for you?
It is common for support to closely work with product and be able to respond with product roadmap and feature guidance.
At least they can say "we sympathize but it's not a priority" or "it's a medium priority but we don't have a concrete timeline" or at least recommend best practices/workarounds
My website traffic was a couple megabytes per month. I paid them for about 3 years for neglegible usage. Should I have zero expectation for paying because its cheap?
You can be metered or fixed price. Mixing the two in the most inuintive way possible is a true innovation. /s
Other cloud based provider have the option to pay for your usage to the cent. I guess that innovation didn't reach the EU. /s
Assuming they've hosted you for 3 full years, I wouldn't mind the 10 euros. Even small sites need all infra to work. The fact that your site is small only means it costs less in transfer.
My experience with all EU providers so far is yes, you do have to prepay, I think Hetzner for exemple was 20 euros when I signed up years ago?
Most likely they are unwilling to let customers pay later without any guarantee that they're good faith and solvent. Maybe it is a cultural thing? It's only my personal opinion but it never struck me as unreasonable.