The phrase "whole packet" means having or getting everything that's included in a set or package, without missing anything.
Sentences with «whole packet»
We hear about women taking whole packets of birth control and washing it down with vodka.» (politics.co.uk)
I suspect I must by now have had about three gallons of gore drained from my left arm, and been repaid with about three whole packets of custard creams. (firstthings.com)
Did you use the whole packet of Trader Joes Taco Seasoning Mix? (familyfreshmeals.com)