Paid twice for 1 flight

Good day I paid mango a flight on the 21/02/2019 for my husband (Yolani Cwala) from Cape Town to Jo burg via cellphone banking, they said they cant see it on their side and he must pay again they will refund him once it appears which it did , we did followups and they promise to pay it within 72 hours they didn't , they asked him to send proof of payments and he did then they said by end of the week he will have his money on the bank, its a month already and still nothing

Please assist with this matter.