A buyer can raise a concern about a payment Otute still holds. Only that payment waits, for up to 30 days, while the seller responds.
While Otute still holds a payment — before it has been released to the seller — the buyer can raise a concern about it from Finances › Purchases, saying what is wrong. Concerns about tutoring hours are raised on the contract itself.
Otute does not decide whether a service was delivered. It holds the payment, makes sure both sides are heard, and applies the 30-day outcome above.