@Katejai72
There's isn't one. If this is to claim a gift you need to use your credit agreement number without the letters as the invoice number. You might also be able to use your Sky account number.
Your credit agreement can be found in your message centre
https://messages.sky.com/message-centre
▪️I AM NOT A SKY EMPLOYEE (undercover or otherwise)▪️
Sky customer since 2001
with: Sky Q | Sky Superfast Broadband | Sky Talk | Sky Mobile
NOTE: I only provide help on the forums and NOT via PM
