There is a 3% tax and then there's a fix charge for a CC transaction so you get charged upwards of 5% on the rupee value of USD. Do not be surprised if you receive a text message quoting a very low conversion rate and then your SCB breeze log in showing a much higher conversion rate two days later.
Try and push your local Post Office to find it as its rare for a reputed seller on Aliexpress to not send a product. They will refund it or even offer you discount to purchase another. In over 30 orders I placed, only one failed to deliver from the source's end and supplier admitted it was their mistake. GPO is getting better at delivering the parcels though. I am not sure about it, but its likely that recent Chinese trade deals with Pakistan have effected all Chinese Businesses with operations/deliveries in Pakistan. I ordered stuff upwards of Rs 10000 a few times and even luxury items but I haven't paid more than 18-30 rupees duty on anything which also points to the same direction.