I can’t help you directly but just to say there are many in your position and some worse.
I haven’t seen my 4 year old twins for a 6 weeks because they are with their mother in another country. Earlier in the year it took less than 14 days to get a passport for a family member so I stupidly assumed it would be the same now. I was supposed to be back with my family long ago but I’m stranded without a passport.
I’m not joking but when I go to sleep I start dreaming about how they manage 10,000 (my estimate) of old passports arriving at their office every day. I drift off thinking about giant boxes filled to the top with hand written special delivery and tracked letters containing old passports and birth certificates and how they manage so many.
A total guess is they have some kind of physical first-in-first-out system of documents taking up enormous space. Once your old passport has gone into that system nobody could retrieve it to make it go any faster because there are literally a million or two old passports there. Until your old passport eventually makes it to the front of the queue its not going anywhere and that would explain why that can’t return old passports to people quickly when they realise they should have applied fast track.
Probably all rubbish but it keeps my brain from worrying. Buy yes the whole situation is bloody terrible.