something is wrong with the system if it keeps going *without* pedalling.
some systems are designed to require you pedal to get any assistance, but *none* of them would (or at least should) ever be designed to require pedalling (or having feet on pedals and not moving them) to *keep* from getting assistance.
as you note, that would be extremely dangerous. aside from the problems while riding, it would also result in lots of damage to life, limb, and property, simply from turning on the bike without already being on the bike (which would be a completley normal thing to do), or getting off the bike while it is still turned on (also a completely normal thing to do).
additionally, every oem ebike i know of has ebrake system cutoffs that disable motor power while the brake handles are pulled past a certain point. if yours doesn't respond to them, something is wrong with it. if it doesn't have them, you can fix that by adding them.
so, something is almost certainly wrong with the system. it could be wrong with an entire batch of them, or even all of them, but something is wrong. if the service personnel refuse to fix the problem, you will need to contact the manufacturer to get it fixed, unless you don't mind voiding any warranties it has (as most manufacturers usually will not allow end-user service and still honor warranty as they can't control what you do or be responsible for it).
for what might be wrong, if you want to fix it yourself, regardless of warranties, you're going to need to do some troulbeshooting, but before we can point you to what to test, we need more info from you.
first, did anything at all, i mean anything, happen between the time the bike worked correctly and the time it did not?
or did it never ever work correctly from the time you bought it from the manufacturer or dealer?
a google translate of the manual found on the page you linked
https://translate.googleusercontent.com/translate_c?depth=1&rurl=translate.google.com&sl=auto&sp=nmt4&tl=en&u=https://www.volta.com.tr/image/dosya/VSM_Kullanim_Kilavuzu.pdf&xid=17259,15700022,15700186,15700190,15700259,15700271&usg=ALkJrhgAathaP6xmw8IDvuSxlk3RyNcC_Q
does not mention any form of pedal requirements at all, or foot placement.
it only mentions throttle, and that there is a kickstand interlock that turns off the throttle if the kickstand is not retracted.
it also mentions that it's wiring is susceptible to vibration failures, so there could be a wiring failure somewhere inside (broken most likely, but shorted is also possible), probably from shipping/handling if the failure was there when you first tried it, or from almost anything if it didn't start till after you'd used it a while.
given the info in your last post it's unlikely, but it is even possible that the problme is the throttle cable wire may run under the cover of the center platform and that it is being crushed/pinched by wrong routing during manufacture, and the additional pressure from your feet is shorting the 5v wire to the throttle signal wire, causing full throttle.
if the system really is designed backwards, it should be possible to simply disconnect the pedal sensor wire to prevent the problem.
