Manuel,
Are you managing these "packs" outside of SmarterTrack? For example, via a CRM, your sales system, or something? Is that info stored somewhere and manipulated/managed as the hours are used?
I ask because SmarterTrack does have External Providers that can be used to pull info into Track and display on a per-customer basis. We do this ourselves and we pull info from our custom Business Management System for each ticket that we receive. If you do manage these externally, you could use the user information provider and at least display their balance in a custom field for a ticket. Check here for more info on External Providers:
https://help.smartertools.com/SmarterTrack/Current/Topics/Settings/SystemSettings/Tools/ExternalProviders
Derek Curtis
COO
SmarterTools Inc.
www.smartertools.com