Medibuddy scam alert- asking extra money post appointment confirmation

So over the weekend, i joined Bangalore's viral fever club. Seeing the fever not curing for almost a week , i booked an in-person doctor's appointment at Indiranagar through Medibuddy. Very soon i start getting multiple calls from medibuddy saying i need to cancel my appointment and rebook it for a higher price as the hospital confirmed they are charging a higher price for it. Not sure how legit this is, but its definitely not a scam n calls r from medibuddy's official number. Can they deny me the appointment if i dnt cancel or pay the extra amount now