savings don’t really count for much anyway they can easily be spent…
Openrent referencing doesn’t need a ‘referee’. What it does is check ID income outgoings etc. They can provide openbanking access then OR can see what they spend each month (and see if monthly outgoings for rent at previous LL) and monthly income. That then allows OR to see if they can afford your rent.
But they should have tax statements from the years that they’ve reported their earnings. That’s what they need to show you. Need at least 3 years minimum to establish that they have dependable earnings.
Best to get other fully employed potential tenants unless there is a compelling reason to take these tenants. Disregard savings. Have 3 years verified tax accounts for self employed. Dont reference all and sundry just certainties. Be 100% sure they have at least rent cover of 3 x times take home pay. Ask all the usual pre-viewing questions and more before even considering offering a viewing or tenancy. Sorry if obvious.