Frustrated with poor service

I was looking for an inverter trolley in the later part of 2022 before the loadshedding really became a big problem and ACDC Express had one at a reasonably fair price - let's be honest, these things are not cheap... I ran a tv, router and two 3.5watt lamps on it and it worked well for about 4 months ( as a 2000 watt inverter should ) at 2 hours a shot when needed. All of a sudden it stopped holding it's charge and would only last me an hour for the aforementioned items connected. I decided to take it back to ACDC Express Pineslopes Fourways, booked it in. The person that helped me stated that they might decide to replace the battery at my expense at roughly R 3500.00 for the battery alone. This means that ACDC offers zero warranty on their inverters and take zero liability for inferior products but happily takes your money in the process.....So having said that, I booked in my unit on 20 December 2022 and after a number of phone calls and a store visit yesterday 24 January 2023....they are now unable to locate my unit - as per the manager of the store. Leaving a message for someone to get back to you is also wishful thinking...Do I take the R12 987.35 loss and move one or do I take this to the next level...what would you do?!