Rumour has it that if you cancel online the miles are back instantly (and certainly has been my experience), but if you cancel via reservations there can be a 6 week wait.

It seems your experience was compounded by being a second refund in the same ticket - thus couldn’t be refunded online - and unfortunately customer service melts down if there are complications that have to be dealt with, most seem to completely ignore what you are telling them and jump to conclusions as to which box it fits into… and not just with SQ, )