Qatar airlines wheelchair assistance can leave you in a foreign country

Scenario: My mother's international flight was delayed by over an hour, resulting in a missed connecting flight. No reason was given for the delay and the next flight was given 24 hours later. As she is disabled, she was booked with wheelchair assistance. However, rude staff left her in a foreign country without transport, food, or accommodation. The flight was operated by another airline, but operated on behalf of Qatar airlines - this sub-contracted flight was chosen by Qatar airlines, and they have used this as an excuse to not reimburse us. However, they left a disabled person in a foreign country to fend for herself for 24 hours. That's not the end. She therefore missed most of the lounge access time I booked for her. Incurring further wasted expenses. And then she was delayed again - without a description - for 5 hours in Maputo. The airlines couldnt give me a departure time or passenger update or reason throughout the many mishaps in this journey.

Excuses: It has now been about 3 weeks since the flight and I have got no result. The only response I have got is a denial of responsibility. And no acknowledgment of any of the delays - just a quick and non-descript denial that they operated the first delayed flight. The customer support agents seem polite - which is great - but they dont actually resolve the issues.