Number type not working corrcetly

Hello,
I’m using premium version and have problems with number type options. I set “Limit selectable elements” to 2 and “Max/Min input values amount” to 8, so I want that my client can select from all options only 2 elements with value of 8.
Problem: Default value didn’t setting up to 0, so if u have 0 on element it calculates like 1 element is chosen.
2nd problem: When u choose 2 elements, other choses are disabled, but not +- buttons/cursors, clicking on them u can choose more then 2 elements.

So main problem is that my client can select more then 2 elements with total quantity of 8.