It is probably the BTS that is either gone bad or turned off for some reason only PTCL can tell. In my experience no amount of complaining will ever yield results when it comes to signals. Going to court wont help either because it is clearly stated in terms and conditions that service is only available in certain areas.
This is unfortunately the state of affairs in Pakistan in today's day and age. I will see what I can do, will make a few phone calls and see if I can get you some information at the very least.
It is just a guess but it may be that speeds have been capped. I dont think it is something which PTCL will own up to though. The best you can do is ask them to send someone to check the connection and device.