Hello If you repair several devices like, Phones, Computers, TAblets and each have different brands and devices. Then you need to use Grouped services shortcode.
Please edit your page of booking and use this shortcode > [wc_book_type_grouped_service]
Then go to Devices and add devices properly to correct brands and device types.

Once you have added some important devices you want to start with. Now it's time to correctly add services with proper groups

So services selected under Installation will show up when user click Installation Accordion title.
Let me know if it's clear or you need more assistance. Thank you.