So I recently purchased a Sony A7ii with the Kit Lens (ILCE-7M2K) from Very.co.uk and applied for Cashback which I believe is around £200 for that model. 

I filled out the Cashback form correctly and attached the serial number from the actual camera as an Image and the Advice Note (Invoice) which was in my parcel. The Advice Note contains the item ordered, value, my details and the date of order. 

Sony then emailed me back saying that I had sent them an online confirmation rather than the Invoice and that now I am no longer valid for the Cashback scheme.

Does anyone know what I am to do in this situation when I have sent them what they wanted and they say it's incorrect?