No refund on returned battery

I made an online purchase for a Mecer 1200 inverter and akso a separate purchase of a deep cycle battery from First Shop the weekend of Black Friday. I paid online for these items. In December 2022 i received an email that the inverter is on back order and that there is no ETA on the inverter. I decided to cancel both these purchases. The deep cycle battery I did arrive by courier but i sent it back because I dont gave the inverter and deemed it useless without the inverter.Tge inverter purchase was refunded to me but now I struggle to get my refund on the deep cycle battery. I have sent numerous emails to them. I feel that the battery must by now arrived at First Shop and feel that I have been ****** of the amount of R2900.