Why worry about that? It's the business decision they've made, and I can see the logic behind it - if they've got you, a customer, on two of their services, and offer you a bundle discount, should you think of leaving them, you'll think twice because it'll be a great hassle: by leaving a mobile service you'll lose the discount on the broadband, and your mobile and broadband contract terms aren't likely in sync meaning they've got a greater leverage when convincing you to renew your contract, plus you can't disconnect both services at once and take a similar discounted bundle from TalkTalk, BT, EE, Virgin or Sky (and Plusnet have just launched theirs). So once they've got you on their home+mobile bundle, you're all theirs and you won't leave. Eventually you'll just get used to having everything Vodafone and won't want to leave eithet. And it's worth more than a couple of pounds they lose by offering you a discounted broadband.
P.S. And if you look at their out-of-bundle charges for mobile... It used to be £1 per minute to call abroad and they've just upped that further - if they're doing that they don't need much to break even
Edited by Mml (Sun 20-Nov-16 18:53:02)