Dear I have no idea about reputable AC technician in the above mentioned areas. BTW peshawar is a big city & full of good mechanics due to bigger car market & availability of parts in Shoba. Search for any good AC technician in Peshawar.
And dont mix knocking sound with oil grade, your car knocks due to bad fuel, use high octane once in a month & u are good to go.
I am using havoline 10w-30 for my vitz & its working like a charm.