Does the persistence of punishment and tribulation upon a sinful penitent mean that his sin has not been forgiven or that there is a defect in his repentance, and what should he do to have the tribulation removed from him?

A servant may repent of a sin, and his repentance may be accepted, but the affliction that befell him due to the sin may persist due to divine wisdom, as happened to Adam, peace be upon him. Therefore, the continuation of affliction does not mean that repentance has not been accepted. A Muslim should blame himself, strive in repentance and seeking forgiveness and doing good deeds, and be patient with affliction, hoping for reward from Allah, for all of Allah's decree is good for the believer. He should also strive in supplication and humble entreaty to Allah to remove the affliction, for supplication is a great means to achieve what is desired and avert what is disliked, and it does not contradict patience, as Ayyub (Job), peace be upon him, did. So, a Muslim repents, seeks forgiveness, and is patient with Allah's decrees and submits to His wisdom.