your account needs to be up to date with a near current reading.

see this:

How do I get a refund from OVO when my account is in credit? | The OVO Forum (ovoenergy.com)

Hey @Buffy13,

Welcome to the OVO Online Community.

Self serve refunds

Customers can request refunds up to £500 via the online account.

You must match the following criteria to request a refund online:

• Have an active Direct Debit with at least one payment received from that bank account
• Check the account’s been charged up to date to actual reads within past 28 days
• Request a refund of over £5
• Request a refund up to £500
• Leave a remaining balance of at least three month's Direct Debit

Refunds can be requested through your online account by following these steps:

• Go to the Payments tab and click 'Apply for a refund'
• Choose the amount they wish to have refunded

As advised in this similar thread:

I would make sure we are in communication with your smart meters as the account needs to have been charged up to date to actual reads within past 28 days.

If you’d like more refunded you can contact our Support Team who can initiate refunds up to £2,000, however if the refund is over £599, we will need to check the account has been billed to smart reads or request photos of the meter. 

If you’re on a fixed rate tariff, you’ll still be required to keep one month's worth of direct debit as credit in your account.If you’re on the Variable tariff you aren’t required to leave any credit on your account, although it is advisable.

Hope this helps. 

I have contacted support team on the web and they give me aohone number to ring. I am having trouble getting through. 

Hey @Buffy13,

Sorry you’ve had issues getting through is this sorted now?