The last false positive we had in BF3 was 3 years back in 2015 so it could also be legitimate bans caused by "silent logging" is when cheat use is detected and logged by PunkBuster software but no action is taken at the time,when the "silent logging" phase is over, Even Balance issue a global GUID ban on every pbguid that was detected during the "silent logging" phase.
If they find themselves that the ban was triggered in error the bans will be removed immediately,If they don't then there's no unban.