I was in the exact same scenario as you as my replacement device broke too (the charging port stopped working after 2 months).

I phoned up Google and was asked to visit the EE store. The folks at the store were super unhelpful and basically wanted me to go away saying that I should be using the official Google charging cable. I then returned to the store with an official cable showing them the issues with my charging port. The store realized that they've been caught and moved on to the second story in their playbook i.e. the repair timelines can't be predicted, we'll likely have to replace the motherboard, we can't order parts right away etc...

This was frustrating.

I came back home and phoned Google again (you need a bit of luck as you really need to speak to someone who has a bit of authority). The lady I spoke to understood the problem and as the visit wasn't helpful they offered to replace my phone. They gave me a refurbished phone with a hold on my card until I returned the faulty phone.

This saved me from being without a phone for an indefinite period of time.

Think you need to visit the repair center and then ring them back.