Terrible service!!!!!

Ive been a regular shopper at your store for my aquarium needs from fish to accessories. Today i was completely blown away by your terrible customer service, it made me feel like an idiot. About 3 weeks ago i came to your store to purchase a better filter for my tank, i have a hexagonal tank that i also bought there. That asside i was sold a filter that was USED. I discovered this when i got home and saw the box was wet and also the filter media had dirt in. Which wasnt a train smash, but the filter was in fact not working which made me angry, as i had to travel back from melkbos again and how can they place a broken and used item for such a sensitive pet hobby as fish back on the shelf!!!! I took it back the next day and they gladly exchanged it for me for another fiter, a brand Ive never used before and assured me it would be 100% adequate for my needs and would perform optimally. Two weeks went by and my tank deteriorated, water turned stinky and green. Trust me i cleaned and cleaned and cleaned and treated. Also i lost 7 FISH!!! the filter was not functioning properly. So i decided to go back today 16th june and get a refund and go to my original aquarium shop... The manager lady immediatly said that they dont do cash refunds and she would have to phone the owner to ask. After that phone call she said that he said he cannot offer me a credit as i have used the filter already!!! I COULD NOT BELIEVE WHAT I WAS HEARING. Based on the fact that they sold me a used and broken filter just 3 weeks back now they will not exchange or refund me because i used the filter. DOUBLE STANDARDS MUCH. The manager was arrogant and rude and not understanding at all and made me feel stupid. She told me i can leave it there so the owner can look at it or take it home and use it!!! BEARING IN MIND IM A TROPICAL FISH OWNER. She basically was going to send me home and watch my fish die off one by one. I merely wanted a refund so that i could go elsewhere as both products purchased there were dissatisfactory..i also asked for the owners numbef so that i could call him and explain my case but the manager lady said he does not take personal calls. THIS IS NOT A PERSONAL MATTER LADY!!!! . Now they have my filter and my money and i must wait until the owner phones me. I will never buy there again. And i will never recommend to anyone. Such terrible customer etiquette. Im going onto hello Peter too.