My upgrade experience (sons first passport) has been ok so far but quite early in the process. Called passport office who passed me through a few people and h then finally confirmed my details, requested Durham as local office. Got an email straight away which I replied to and received an automatic response, I then got a call about 2 hours later from the Durham office to say they had received the upgrade request and be in touch in 48hours. Just waiting for that call back. We don’t fly until 9th may.
In the meantime I got an email saying they required further documents (my marriage certificate) as the name on my passport and on my sons birth certificate didn’t match up, sent that next day signed for. So I have everything crossed I will hear something tomorrow