Builders - What Customer Service ??????

Purchased an Ellie’s inverter for our 83 year old Mother to help her during load shedding in sept 22. It lasted 3. 2 months. In January I took it in to the Builders Gezina repairs department. They said Ellie’s would collect from them on Friday. 2 weeks later they called and asked for the proof of purchase as well as their own receipt for the return which I sent and now NOTHING! IT seems as if the inverter is LOST ????? ELLIES called me this morning to ask “where the inverter is? “ what the hell??? My Mother is stuck in load shedding stage 6 without the expensive inverter and not the Supplier or Manufacturer knows where it is despite 20 calls from me to the Builders care centre asking for follow up and no one calls back with an ANSWER !!!!!!!