I spoke to Cupra again yesterday and they have asked me to go to the dealership to carry out what is effectively a full reset, but after reading a post on the Cupra Facebook group, I tried again tonight and it's now working. This is what was posted:
The communication between your vehicle and the backend was disrupted, resulting in the OCU (Onboard Control Unit) failing to transmit information to the servers. Consequently, the services were inaccessible. To address such issues, the OCU is designed to handle them proactively. It automatically reboots every 8 days to resolve any potential problems that may have occurred during that period. After the reboot, your vehicle successfully resumed communication, as we have verified.
So given there's an 8 day reset period of the OCU, any problem should be fixed after that time. For me it was 9 days ago that the car stopped communicating. so after doing the swap to the guest account and then back again, it all kicked in to gear again.
Just thought I'd let you all know.
