MPOWA Finance said my payment is not recognozed and now they are refusing to refund my money.

I've had a bad experience as I took money in December and I missed payment cause I could not use my expired card. So Mpowa sent me banking details and reference number and told me I needed to make a payment urgently, of which I login to my other bank and made payment as they have advised. Once the payment was made, I downloaded Proof of Payment and emailed them then they responded that my payment is not recognized because I did not use the bank card that had expired.

Now they are refusing to give me my money back which I have already paid, because if my payment is not recognized they should bring my money back and now they are giving me stories I am extremely frustrated