London - Shanghai - Japan - Shanghai - London

Hello, I am getting conflicting information from the London Chinese embassy in London and wondered if you could help.

My partner and I are travelling from London to Shanghai Pudong on 19th April - 23rd April (with UK and Irish passports). We will then travel from Pudong airport to Japan 23rd April - 5th May. We will arrive back in Shanghai on 5th May and leave for London on the 6th May.

I was told that I would need to ring the Shanghai port authority to pre-check my travel arrangements are valid for the 144 transit exemption and get confirmation.

However, when I checked the number they gave me it was for the cruise ship terminal! Do I need to get confirmation from the Shanghai authorities before travelling? Or can I just "apply" for exemption when I arrive in Shanghai as per your diagram.

Many thanks in advance!

Laura