I guess, they are just lazy.
Keep bugging them, tell them you need to apply for registration asap, other showrooms do it much faster etc.
When they grow tired of you, you will get the invoice:)
That's how to do things in Pakistan, i stayed 2 hours in PTCL office today, and i took the line-man with me to get the job done, before that, i had to wait 2 weeks.