[Raccoon]

You've over-complicated the SE by providing more details than required, which (as you've experienced) Is not good practice.

I gave away the battery and smartphone to a friend of mine who is a mechanic to dispose it

Tell them that you've Immediately contacted your friend, and he's yet to dispose of It. Comply with their request thereafter.

Before i told them about disposing the phone, they asked me to return the phone by going to the post office or through a pickup from the carrier at my home, that's why i told them about the disposal.
If I say them about having retrieved it, they would ask me about shipping the phone back to them, what should I do?