Sita bus stop at piano di sorrento

Rahul, have you asked a local for directions? Are you staying in a hotel with desk staff which can help you?

I think you may have to take a local EAV bus or the Circumvesuviana train from Piano di Sorrento to the end of the line at Sorrento before switching to SITA bus. See also http://www.sorrentotourism.com/en/ferry-and-jet-services.php.

But Google Maps does show a bus stop/station on Corso Italia near it's intersection with Via S. Sergio and Strada Provinciale Mortora S. Liborio.