It's taking this long because PTCL changed the way that numbers are assigned with GPON. Instead of just having one landline number, when a new GPON account is created, one PSTN number is assigned, which is the one you'll call from and which will show on others caller ID, and one 'virtual number' which is used for billing purposes and account management.
The virtual number is longer in length than a regular 051 pindi/isb number and can NOT be called.
The reason for this is that GPON allows users to have 2 PSTN lines on one connection. Since all the ONTs being provided have 2 RJ11 telephone ports, they can configure it in such a way that you can get 2 landline numbers over one physical line.
Since people in your area want to keep their old landline numbers, they have to merge their old existing accounts with only one number, into a GPON account with a PSTN number and one virtual number. That takes a lot of extra configuration, and I imagine they have to do it for almost everyone, so it's no surprise they're delaying it.