I consider the overall cost of the phone over the 2 year period. Even if I go by your logic I paid £355 for the phone (Samsung S9).
Because you're not paying £816 for the phone, you're paying £408 for the phone and £408 for 30GB data.
£408? Why would I compare to £408, when this deal costs £816 over 2 year period. I got S9 for £710 cost of 2 year. Hence, the comment.
Cheap but Vodaphone
Please share this deal. I'm looking for an s9