As you should know by now you have a HC.

And that HC is secured at the start of play.

If the comp is then played and the team after deducting the 3/8ths difference uses a higher amount of shots than is allocated by the book, bad luck on team that lets them get away with it.

Rule: 6-2a/6
Wrong handicap allowance used in match.

Answer

The Committee should rule that the match stands as played.
The players failed to take note of the conditions of the competition (rule 6-1) and have only themselves to blame.

We all try to learn this game , but it takes very little time to read the rules, before a comp?

Sorry about that, maybe you too will read the rules before playing again?