Sterling Hospital — Not providing the discount amount which is against rules

My father was admitted and at the time of discharge, we were presented the final bill along will cashless approval letter ( final authorized ), based on rules it was clearly mention to the hospital to not take 10% discount amount from the patient ( 10% discount amount on total bill which comes out to be 62, 000+ Rs ). They said as per sterling policy discounted amount will be provided in form of cheque on patient's name post 2 months. Now the cheque has arrived of just 6440 Rs that too this amount was taken in access and hence the same as been refunded. But what about that 10% discount, they were suppose to give on day of discharge itself but the billing team clearly told that hospital will provide discount post 2 months complete discount amount. Now they are denying it that they will not provide. I have all letters bills with me and will surely escalate this higher level