I purchased the Sony AF8 from Currys which promises 2x free 4k movies but there's nowhere to redeem the offer.

I've opened the offer in Sony Select but this only says what the offer is, then when I enter Google Play Movies & TV it doesn't mention the offer anywhere.

Anyone know what I should do ??  There is a valid method of payment in my Google account so that won't help.  Seems a bit of a daft offer if there's nowhere to redeem it...