Momentum Health Refusing to pay hospital accounts

My Husband was hospitalised on the 30th of September 2015. My medical aid option pays IN-HOSPITAL accounts up to 200%. When the practitioner (Lake Smit & Partners) sent me an invoice I contacted Momentum immediately in order to be advised why they had not paid. I phoned Momentum and followed up with emails on several occasions and they informed me that my query is receiving attention. The last response received from Momentum was on the 14th of January stating I must request a referral note and scan report from Lake Smit,which I did.I am not sure what was communicated between the practitioner and Momentum but the email I read this morning, from Momentum, states that I have to pay the bill myself because the account is \old\". How can the account be \"old\" when I communicated since last year about the payment. Why are Momentum case managers not carrying out their jobs fully? Why must an in hospital patient request a referral note or scan report? The medical usually liaises directly with doctors and informs me if there is anything outstanding from my side that needs attention. The 'broken telephone' system Momentum is using off late seems like a scapegoat for them not to make payments."