2nd final bill 8 months later!

Obviously I can't be certain as I can't access your account.

But that does seem clear cut from what you have said.

The period 25th March 2021 - Feb 2022 is more than 12 months before your Final Bill in April 23 you mentioned in your first post.

Under the back billing legislation that is unlawful to try and bill you now for that period.

In your situation given what you have said I personally would put in a complaint, outline all the details and ask for compensation, typically something around £150.

I wouldn't personally wait for ovo to complete any investigation they have already started.

What they have done appears unlawful.

I would also ask them to make sure your credit rating has not been adversely impacted.

https://www.ovoenergy.com/feedback

@Emmanuelle_OVO may have some more suggestions.

You can include a link to this thread in your complaint 

https://forum.ovoenergy.com/switching-suppliers-and-moving-home-144/2nd-final-bill-8-months-later-16588

Here is an ofgem page on back billing

https://www.ofgem.gov.uk/information-consumers/energy-advice-households/check-energy-back-billing-rules

And here is some text from ovo

What is a back-bill?

We send a back-bill, or ‘catch-up’ bill, when we haven’t charged correctly for energy use. This can be through inaccurate bills or not being billed at all. Back-bills can be for any amount, and may be a result of:

• Technical or human error on the member's account which has meant that a statement hasn’t been received within the regular timescale
•  A customer has provided a reading that is higher than previous estimated readings used on their statements.
• Mismatch between the data OVO holds and the actual setup of the meter for example crossed meters, or if a customer had a meter exchange which wasn’t updated before the switched to us

What is a Back-bill Write Off? 

Where we've issued a back-bill for usage over 12 months old, not covered by payments made at the time and the reason for the delay in this billing is not the customer's fault, we'll apply a write-off. This back-bill write-off will be a credit applied to the account to cover the difference between the updated usage and the payments made at the time.

The main situations where we'll write off usage prior to 12 months ago are: 

• We haven't billed the customer
• We've billed an account but not for all usage at the property i.e. only one fuel was billed
• We've billed the customer inaccurately due to a technical or administrative error