Lack of interest

I had notified discovery of cancellation of membership in March for April. The remainder of the medical savings account is supposed to be returned to me in 3-4 months after any further claims. There has been no further claims on this account as my new medical aid covers it. I am now being told to wait a further month for payment to be made in bulk, this should have been included in the august bulk payment. This now makes a total of five months that discovery keeps MY money instead of MY savings being invested by me and earning interest at least. The accounts department is prompt to receive money but takes no interest in returning what does not belong to them.