Benefits confirmation

I phoned Bonitas to confirm benefits for my 86year old Grandmother. It was confirmed she has benefits for her hearing aid, a amount was given for how much her limit was and i asked them if she can go for the hearing aid? Yes i was told. So after this conversation i make an appointment for my Grandmother at the ear institute. We take her and the reception lady tries to confirm benefits with Bonitas where she is told there is no benefit. Only in 2023. This was confirmed twice. Now why wasnt this told to us when i phoned to confirm benefit in the first place? Or does Bonitas enjoy upsetting 86yr old people and making them cry?