Getting the Warm Home Discount after switching supplier.

How do OVO pay the Warm Home Discount to those who qualify and were OVO customers on the qualifying date but have since switched supplier?

Do they issue a payment to the ex-customers bank (if they had been paying by Direct Debit),
or do they issue a cheque,
or issue a voucher that can be redeemed at a Post Office/PayPoint shop?

From the Ofgem guidance on the Warm Home Discount:

https://www.ofgem.gov.uk/environmental-and-social-schemes/warm-home-discount-whd/eligibility

Some customers, for example prepayment meter customers or Core Group customers who have since switched supplier, may receive their discount via a voucher or cheque. In most cases, vouchers can be redeemed at a Post Office or PayPoint shop (however this may vary depending on your supplier).   

 

Will I still receive my rebate if I switch suppliers?
 
Core Group
If you were with a participating supplier on the qualifying date for a scheme year and were eligible under the Core Group, the supplier you were with will be instructed to pay you. You should contact the supplier you were with on the qualifying date to check they still have your contact details and to ask how and when you will be paid the discount or receive the voucher.  

Of course you should wait for the letter from the government confirming your eligibility before contacting your previous supplier.