With Elal Protect, I have changed flights multiple times. Sometimes we call Elal for them to do the change (when we fear we will lose our existing seat on the old flight as well as on the new flight) , and sometimes we do it directly via the Elal site when the new flight is months in advance and we are not worried about being locked out of specific seats. No change fee and no voucher. One can of course cancel and get a voucher to use a few days later to book a new flight.