Return traveling document from home office

[Prince35]

I applied for leave to remain in the Uk January 2017 and by November I got a refusal letter with right to appeal, I appealed late after 14 days period and my appeal was turn down; right now I ve left Uk to my home country willingly on my own using my National Identity card to travel out of Uk. I ve called the home office severally to return my traveling document(passport) but all effort to no avail.
Pls can someone suggest to me on how best I can get my passport post back to my Uk address.