Yeah, the eleutheroi towns with a population of 650 and garrisons of 3500 are a @#%^. Since I consider it inaccurate, I deal with it the same way: when they eventually generate a new unit outside the walls (probably because the stack's full) I just attack that and deal with the reinforcements in the open field.

Worst tactic of all in that situation is to drill the single unit with 2-3 cavalry units right off the bat. If you cause them to rout before the reinforcements enter the battle, you wipe out a few thousand enemies without even seeing them....

-red-