Device booster Discovery sham

I activated my device booster benefit, for a device I had bought 3 weeks ago. The terms and conditions state that you must purchase your device within 30 days of activation, nowhere does it state that you cannot activate after having already purchased your new device. Yet, the second you pay your activation fee, you receive a message saying, oh , by the way, this does not apply to already bought devices. Vitality hardly responds when I query this, and reply by attaching their unclear terms and conditions, which I read more than once before activating the benefit. As if the Discovery executives aren't laughing their way to the bank already, Discovery now refuses to activate my device booster AND/OR to give me a refund as a result of their purposefully vague terms and conditions. Neither of which will cost them a cent, instead they prefer to ***** from their customers. Unacceptable and *********.