Medical Insurance

Please check the sentences below and advise me if they are grammatically correct.

The hospital informed me that our medical insurance company declined pre-approval for blood test for Vitamin B12 because they said that these vitamin tests were not covered by our medical insurance policy. As per the benefits provided, it should be covered by our policy, but I don't undetstand why did they reject it since it is included in our medical insurance cover, and I really need to do the test as I am suffering from severe joint pain.

I request you to look into the matter and arrange to get it approved.