That sounds a real pain but no one here has access to your account so you will need to get in touch with customer support. 
I'm told chat is fastest .. if you type Agent it should connect to a person

https://www.ovoenergy.com/help#contact_us_container

Out of office hours, social media is often still available. In the past, I’ve used what was Twitter 

Hey @Imactuallyannoyed,

I’m sorry to hear that you’ve had issues with your supply. We do have a banner pinned to the top of the Forum which gives you the best contact options for those out of hours emergencies and i’ll link it below so you have it for any future issues: 

As @BPLightlog has pointed out you can reach a member of the team through any of our Social Media channels over the weekend:

Whatsapp - 0330 175 9695

https://www.facebook.com/ovoenergy/

https://x.com/ovoenergy?lang=en

https://www.instagram.com/ovoenergy/?hl=en

Opening hours:

Mon-Fri 8am to 8pm

Sat-Sun 8am to 5pm

If you reach out to a member of the team and let them know that your meter keeps changing modes from Pay Monthly to Pay as you go. They’ll do some digging and find out what’s causing the issues for you. 

As long as you had credit at the start, even emergency credit, you won’t lose power during these times:

• During the night – between 6pm and 9am, Monday to Saturday

• Saturday from 4pm through until Monday morning at 9am.

• All day Christmas Day, Boxing Day, New Year’s Day, and Easter Sunday

For more on this, check out our handy article: https://www.ovoenergy.com/help/article/run-out-of-credit-at-the-weekend

I hope this helps and if you have any follow up questions we’ll do our best to help you.