I contacted this email to cancel my plan. This was a few years ago so it might have changed.
service@hotmobile.co.il
I used this email a few months ago. Sent an email in Hebrew with phone number and last 4 digits of cc on file and told them to cancel. 3 days later they sent back asking me to confirm that when I cancel blah blah blah. I said (in hebrew) yes please cancel, and they canceled it.
I think officially you also should send in tz associated with the account.
