Outstanding account over 70 days

a Sandblasting and prime job was done to one of Kencrete cement trucks on the 23 September 2019 to an amount of R15600. This company refuse to pay SS Sandblasting because there financial department made a payment into a wrong account and now refuse to pay until this money until they get refunded by the bank. We communicate with them for over 70 days now as this was not our fault as on their invoice our banking details was clearly stated in RED. This is not fair that we have to pay for a mistake made by them. Please help us to receive payment