HiFi Corp, no response to inferior quality inverter for weeks.

Last year July (2022) I bought an inverter from HiF online for delivery at my mother. This process was effective and the item was delivered quickly. The inverter worked quite well as expected. In Dec 2022 the inverter started to reduce significantly in back-up time. On 22 Jan 2023 I logged a call about the issue. On 24 Jan item was taken to a local HiFi Corp branch in PE. Then wait started. No communication from nobody. When you phone the Baywest branch, they freez-up and know nothing. Someone will always call you back, which never happens. I called the national help line. They "re-opened" the case. Still no action. I emailed HiFi, they rep**** to say they will contact PE. No further reply. I asked again this morning, 13 Feb, via email what's the status, no they offline. It's afternoon now and still no reply. HIFI Corp Complaint *** - *** and Baywest paper ref: HF-LALE-***