Pitbull have unlimited stun granades?

What is the problem? all units with emp can use it (freeze) multiple times, but not on multiple units simultaneously. The first unit that comes in range is frozen for some fixed time (depending on unit's health). After that fixed time expires (it's like a emp recharge time) the unit can freeze again and does so once somebody comes in range. This is true for offense and defense units.
This is a feature, not a bug.
This is how e.g. GDI anti-taxi defense works: line of snipers behind a line of pitbulls at the back - pitbulls freeze infantry, snipers kill infantry due to longer range (all other units are killed by support weapons) nobody can make any damage to those two lines of defense at the back.

Can't say that there's a change in the number of grenades that each unit carries. Both Riflemen, Orca and Pit-Bull has access to grenades. I know they only work once on the closest applicable unit. Seems better if the grenades have 2 or more charges. To avoid your units being stunned to death, consider adding 1 of each artillery units into your base. It will make it extremely difficult to assault your base unless your enemy has a higher offense.

I mean Pitbull's in defence :) Cant use infantry if I launch revenge-attack vs guy with Pitbul's.

I didn't know Pitbulls in defense can do that... well, maybe @gamerdruid can explain the issue to me and why defensive Pitbulls are stronger than Offensive ones. Aren't they the same unit? One's on base duty and another on the field.

Maybe @EE_Elephterion is better placed to explain such things.

Well, if we want to weed out the bugs and quirks involving the upgrades, we should definitely have more RP and Credits given to each account at the next PTE reset. I mean there should be enough to research each one so each can be tested individually. Does anyone find the Vert/Hawk's upgrade useful? I was thinking of having it replaced with something that would make farming easier... maybe we should have a community poll that asks which of the worse upgrades are deemed for replacement. Top 5 picks get replaced.

i remember a pit bull continually over and over stunning the same infantry troop during the same attack before. it is an odd situation to reproduce for me currently because it was like a "taxi" attack you know where basically everything killed by supports. it actually was the only defense ever i seen that could defend against that type of attack. like i said though the one pit bull stunned that same infantry at least 5+ times in just one run

as an example it was similar to how the mg's on the fortress will stun a salamander or cobra multiple times

Stunning the same unit 5 times in a row with the same defensive unit is kind of game breaking. For example, a strong offensive unit could be prevented from moving if the defensive unit spammed stun grenades rather than attacking it. All other ground or air units behind it would get locked into waiting if the stunned unit is a ground or air unit, respectively. We should have a check where the unit with the stun grenade has more than one charge but the twist is that the unit with the stun grenade can't stun the same unit twice. It has to be a different unit, whether its an offensive or defensive one.

Thanks for the details commanders,
so far this seems to be affecting only defense units, where any of you able to observe this for offense units?