remove spy until it is better

[Sundance]

Multi use implanters are bad, also just have the ringleader have the names of his crew so he can contact them.

That's very simple, and could actually work very well. It'd make hackers (i.e: PDA tappers) highly useful, where before it's not so much.
The only problem I could see with this is
A) The ringleader would just take down the names from list, and not bother contact them via pda.
B) Once contacted, the spies will destroy thier pda's to prevent any back-tracking.

add a feature to spy leader PDAs where they can anonymously message teammates when they unlock it

No no, the whole point is that capturing pda's are a pitfall to spy leaders.

There needs to be a solid way of combating A and B, and then that could actually be a solid fix
Suggestion:
A) Have the contact list on the pda messager come up as
-->Contact 1
-->Contact 2
etc
This way they'll be forced to contact them, to find their name.
B)There needs to be something connected in the round to the PDA that stops them from throwing it away. Hit two birds with one stone and have information stealing as part of the objective. Put info (i.e: Code: 5hj90jga0n) onto the pda, which other spy leaders need to capture to complete an objective.