If you're claiming that two balls went into the 210x but you were only paid for one, you would need to provide the seeds for both balls to verify the outcome. That particular ball that went into 210x but only paid you X, you'll need the seed for that

On a related note, users should not have to possess advanced technical knowledge or contact customer support to verify the provable fairness of a game, casinos should have this information readily available and easy to understand for all users.