It is quite common for ISPs to make this type of offer to new customers only. It is a way of attracting customers to change brands.
I wouldn't describe it as "unfair" but I can understand why you are cheesed-off.
AMD Radeon Adrenalin release date, new features, compatible graphics cards
Inside the iMac Pro - Apple's most powerful Mac yet
iMac Pro release date, UK price & specs
Comment nettoyer Windows et optimiser son PC gratuitement ?