How to receive visa to leave Russia? (St. Petersburg)

Hello! My doughter was born in St. Petersburg 6 weekes ago. We have just received information, that we should leave Russia to get russian visa in Poland. Here we could not apply for the visa...
But how to get out with a child who doesnt have russian visa at all? We called on the border and they told us, that we must have a special visa to get through the russian border, which we should receive in FMS. But in our FMS they dont know nothing about visa to leave Russia, so thay told us we cant receive it.
Does somebody know where we could receive this kind of visa? Please help.