IMO maybe two versions, real handcuffs that cannot be broken unless you have help, like a blood transfusion. And the plastic zip tie ones, which can be broken on your own with time, 15-30ish seconds, and you make pain sounds when you try to escape.
I don't have a problem with the zombies being too many. I do have a problem with the jerky movement and being unable to shoot them because they teleport around, and no way to loose them or defend yourself after you run out of ammo. Keep the numbers i say!