Promised upfront but then full of stories

I have been with them for 3 years and paying my monthly installment on time each month. Only used it for a few GP visits in the past 3 years and now for the first time using it for something else they rejected my claim stating that my policy doesn't cover the mentioned claim. But on my policy schedule I am covered for Radiology so when I send them various e-mails they came back with a list of codes that they cover under Radiology, which was never mentioned or provided when I joined.