What should someone do who swore an oath seven times concerning a single matter and was unaware that the expiation is only one, and was ignorant of the condition of sequence in the expiation of an oath, and fasted 12 days out of the 21 days he had intended, then learned about the condition of sequence and the single expiation at the end of the period, so that Allah may accept his expiation?

Order is a condition for expiation, and it does not multiply if the oaths are for a single thing. If fasting occurs at a time when surplus money beyond one's needs is available, then the fast is not sufficient, and expiation by feeding or clothing becomes obligatory. However, if the swearer was unable to feed or clothe at that time, then fasting is sufficient. If an oath is sworn again, even for the same thing, after expiation has been performed, another expiation becomes obligatory.