Asked for it back 5 June, reported no receipt 26 June, both via the online return of documents form. Sent first round of complaints 29 June, second round of complaints 6 July. Contacted MP 7 July, spoke with MP's parliamentary assistant 8 July. Received a written reply from MP 10 July stating he had written to UKVI's director general and his assistant would make a follow up phone call this week. Received an email response from Home Office Treat Official Team (follow up to the email I sent to
ministerforimmigration@homeoffice.gsi.gov.uk) 13 July to say the department responsible had been contacted and I would get my passport in the next few days.
We'll see what shows up in the post by the end of this week...