Midlands_Solar Sorry, reading back, you say that consumption is correct, despite not having a connection. Oh... well, maybe it did use the meter data as a fallback ?
I can't remember where the portal gets tariff information from - mine gets it from Octopus since I've given it my Octopus account details. If you've had to manually enter your tariff details, perhaps you made a mistake there? Presumably prices changed on 1st April - perhaps you edited them and made a mistake, such as entering it in pence instead of pounds ? 13.25p/kWh would seem more plausible than £13.25/kWh. Then the internet being down would just be a coincidence.