Refund me my money!!!

I contacted Rentoza on 23 July advising my device is eligible for buyout and instead of them deducting the normal monthly installment they should send me a link for the buyout price. I was then told they would get back to me, but instead of them getting back to me as stated they deducted the installment and have since not refunded me the difference. I habe sent several emails and requested for assistance on social media but nothing! I am also due to receive a refund for a device they declined me for, there is no communication given about any of my refunds, nor any number I can contact them on. This is beyond pathetic. All I want is MY money that is lawfully and rightfully entitled to me