Incorrectly paid supplier twice instead of reimbursing and blames member for incompitence

Incorrectly processed a claim twice to the supplier instead of to me. Proof of payment to the supplier was provided as well as a statement of the payment from the supplier after the first incorrect payment. After complaining, Momentum decided to pay the AGAIN. So now the supplier was paid twice and I remain out-of-pocket. There response to the second complaint about the second error results in them telling me it's my problem, I must use the credit somehow with the supplier and it's my fault that they did read my emails or read the receipt/statement correctly...