Strange - illegal batter or what

[homerun70]

I wonder if there anybody know how to solve my problem. I'm an umpire in our league (Slovenia - Europe). We're in finals (games for 1st and 2nd place). Today happened something new for me.
Situation:
- runners on 1st and 3rd, enter player for home team with No. 87, which does not exist on line up and even not on rooster for that categorie (senior) - No 87 played for cadets (12 - 15 years old).
- opponent apealed for that batter after his turn (No 87 was Striked out)
- home team made a substitute for that batter and put the propper player instead of him.
- opponent requested for winning the game after that mistake of a home team, they wrote a protest for that action happened with player No. 87.

The question is. Is the game suspended or not? Is the game ended with winning of a opponent team? What shall I do? Or what can I do? Please help me in that furious situation.