class LoyaltyCardService {
    // constructor removed for brevity's sake
    
    void addPoints(int id, int points) {
        LoyaltyCard card = //... find card by id in db
        card.addPoints(points);
        // persist the LoyaltyCard
    }
    
    void removePoints(int id, int points) {
        LoyaltyCard card = //... find card by id in db
		card.removePoints(points)
       	// persist the LoyaltyCard
    }
}