So an update from last week.
(Application submitted and received on Monday 6th July, passport delivered on Tuesday 7th July, nothing heard since)
Saturday 11th and Sunday 12th – Sent various tweets and emails (including to my MP)
Monday 13th July – Nothing
Tuesday 14th July – Nothing
Tuesday 14th July – 3pm called the passport advice line (0300 222 0000) and asked to make a complaint. Spoke to a really helpful man who took my details and said that he would follow up my application with Durham. I also had to email him proof that my travel plans had been booked before March (they were booked in January) 2020.
Waiting anxiously, but trying to remain hopeful @Mattw11 your experience gives me hope.