Referral Code issue - 'This offer is only available for new customers.'

[JessyBean]

I recently signed up for Sky Broadband. During my initial set up and call with Sky I was notified of the referral process and told that I could use my account number for rewards.

I have a family member also with Sky so they provided me their referral link. I input my new account number to active but received an error message; "Sorry! This offer is only available for new customers." But I am a new customer? How do I make use of this referral/new account reward for me and the other household?

[daveNOS]

@JessyBean The referral code must be used when ordering the service initially; it cannot be added after an order has already been placed.