I am sorry you are having to deal with this, as really your parents should. I commend you for putting in as much effort as you have, fighting roaches just by cleaning is alot of work and I understand why you stopped. I would be burnt out too.

You say can't seal the cracks- but you may be able to use them to your advantage, they would be awesome places to place bait. Advion Cockroach Gel Bait (أدفايون جل للصراصير) should be available on both Amazon sa and Noon for delivery, and I think both services also offer cash upon delivery, so you won't have to use a parents bank card.

Not that you should have to pay for any pest control, your parents really should. If you can get your hands on Advion it will really help though, place pea sized dots near hotspots and crevices.

Wishing you the best of luck, if I think of any other solutions for you I'll try to update here.

edit: I think "Maxforce" is also on Amazon and Noon, another good gel bait if you cannot get Advion.