Worst Customer Experience I ever had

I bought a Gizzu GPS300 from CaCell. The device is not working as it is suppose to, for the intended use. To power a 16ch Hikvision DVR with 9 cameras connected and a 24" JVC TV screen, uninterruptedly! I wanted to connect an additional 24" Dell Monitor. The power station is not even running the Dell Monitor alone, uninterruptedly! The device went back to the supplier, but they cannot find the fault, running the "same" setup. The supplier would have contacted me, which they have not done to date. According to the report, they ran it on a 2 hour cycle. Yes, the unit runs for 2 hours correct, after that it depletes... Tested it myself over the course of several days, and the results where the same every time. The unit was collected Monday the 18th of July. The supplier did not give any feedback / did any fault finding, till the morning of 21 July when I followed up... (bad for a customer to follow up) Waybill was created on the 25th for delivery of the Unit, only received it on the 28th. Wonderful customer experience, isn't it... The power station is still under it's 1 year warranty. CaCell does not want to refund me. They ignore all communication to them.