The Daily Grocer Amalinda worst customer service

My sister bought a gas cylinder from the Daily Grocer on the 24 June 2021 at 18:30..she left for Cape Town on the 25th June midday. Came back on the 3rd July afternoon. Last night the gas was finished. She immediately called them and was promised to be called back. Today she called again and spoke to Chris who was extremely rude towards her. She was told that it's her regulator that was faulty. Question is : 1.the gas is used only for the heater and normally lasts for 2 and a half months. 2. The store management is telling her as the to contact the supplier herself. Whose responsibility is it to enquire 3. Chris (who said is the manager) dropped the call on her twice while screaming at her and being very rude, is this how they treat customers?