How to fetch data from a website using LibreOffice's Calc?

Question

I'm searching for a way to fetch some data from a website using LibreOffice's Calc.

I was using Google Sheets with the IMPORTXML function before, but because it's very unreliable I want to use Calc instead.

My functions there looked like this:

=IMPORTXML(E2; "//h3[@class='product-name']")

=IMPORTXML(E2; "//span[@class='price']")

As you can already guess, the URL was in E2 (f.i. http://www.killis.at/gin/monkey-47-gin-distiller-s-cut-2016-0-5-lt.html).

In Calc I've tried =FILTERXML(WEBSERVICE(E2);"//h3[@class='product-name']") only to get #VALUE! as a result.

My LibreOffice's version is 6.0.4.2 with German locale. I use English function names with ";" as a separator.

So what would be the equivalent for this function in Calc and how would the appropriate command for the product name and price look like?