I am never doing an online purchase to tickets at cinecentre!!

On the 14 of March I tried to buy tickets online the payment went through on my side but there was an error and I never received the tickets or my refund.A week later I reported the matter a cinecentre in the midlands and the lady assured me that I should get my refund and f i don't get it I should come back and they will assist me. I went back a week later only to find that they can't help me and i need to call the call centre, I then called cinecentre to get assistance and I was informed to email screenshot of the proof payment to their email and a week later there was no feedback and I still hadn't received my refund I had to send them a message to remind them that I was still waiting for a response on the mail i previously sent only then was i requested to send my card number and its been over a week now and I still have not been assisted.Today is the 15 of April and I still have not received my refund!!! I feel that it is so unfair for myself as a customer to be inconvenienced like this as if the online error was my fault and now I don't even know how long I need to wait to get my money back.