I have a solution for this problem as i had the same one.
After numerous of mails, i always received response from bots, account permanently blocked bla bla..
This is the way
You must submit a form/request on viber, go to viber site and then at the bottom of the page is a contact us link.
Make a form with someones active viber number. Not your own that is blocked.
Make a fresh email and add that also in the required field. Fill all and in the box at the bottom write your sad story and give them your actual number that is blocked. That way a message wil get to a person.
Worked for me
You should receive a response that the number is usable after 24 hours but if its blocked again there is no help afterwards.
And to prevent blocking please update only via google play.
You should update what's app also via play store. To prevent same problems.
To get viber properly, install now and wait for an update from play store, after update submit your request to viber. Cheers