Aetna review: Double payment of a monthly premium.

Switched from a Aetna zero premium to a monthly premium. With premium to be taken out of my monthly social security retirement check. Received a statement bill from Aetna for first month. Not aware that social security would withhold the first premium from my check. So I made the first month's payment thru a direct pay with personal check. The issue is Aetna refuses to issue a refund for the double payment. The crux of the issue is aetna can't understand that social security premiums are withheld from retirement checks a month behind. Therefore, they received an April payment from me in April for April, the received a credit payment from social security in May for the April premium.