DISCOVERY VITALITY BENDING/BREAKING THEIR OWN RULES!

Now why would Discovery Vitality Decide to bend /break their own rules when it comes to the cashback percentage ? Like all the months before this month I attained Diamond status wrt to my Vitality Drive. That according to Discovery should give me a cashback percentage of 25%. I received this percentage in the previous months correctly. This month Discovery decided my diamond status is suddenly going to get 17.5%!!***? Would like to know when the rules/percentage cashback has changed. If this is the case, then it is no longer viable to continue using this Discovery offer as it offers little value/enticement to continue with exemplary driving. Money making scheme again. They wait until you are comfy with the system and then they strike!