Who told you that HEC Islamabad has the sole authority of academic docs's attestation? Nevertheless, HEC regional offices i.e. HEC Lahore can also attest your docs.
Yes IBCC attest docs upto inter level and HEC attest higher degrees. Then, you have to attest all these docs from foreign office in your city of residence. But, I think this process is necessary before going abroad for a job. Pursuing higher studies abroad doesn't require such a tedious process.
P.S.: HEC take some hours to attest all the docs.

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"Whomever Allah guides, no one can misguide, and whomever Allah misguides, no one can guide." Al-Qura'an.