Mr D took my money even though the order failed

I ordered off of Mr Deliveries app on the 29th of May my order failed to go through order number (DFD***4) but the money was deducted off of my account, they have emailed me on the 30th of may apologizing for the unexpected error and gave me a R75 off coupon but the money was still not reversed back into my account which was R355.75. Tried phoning them numerous times but can never get hold of them.