Omega Deep Cycle Solar Battery

I have bought a Omega Deep Cycle Solar Battery via Takealot. It was delivered 30 May 2023 and I started using it with the Inverter I have. One Tv and a light and my Cellphone charger linked to it. The Battery was working for 6 months and then started to deplete. The guarantee was also only for 6 months. In January I contacted Takealot to find out who the supplier of the Battery is. I phoned Canopy Hawks and I talked to a person Juan/John. He said that I can speak to him with regards to the Battery that lasted only for 6 months. Currently it is keeping the inverter on for plus/minus 20 minutes. I paid R3599 for this battery. I gave him my opinion and he said to me that he is not able to assist me and quite arrogant about the whole situation. I asked him if he thinks I must buy a battery every 6 months and he could not answer me just saying that is what it is. When I said to him that I will report their business on this platform he did not mind. He said to me that the battery was imported from China and they are not supplying batteries any more. Why did they stopped? He said to me that I am the only person complaining. And he cannot say what I have linked to the battery therefor he will not assist in any way. I was really so proud of this item that I bought, but then was so dissapointed when it only lasts for 6 months. How can it be? When I really did that was said to me by not linking any other items to the inverter and battery.