Pathetic service from Mango airlines

My 90 year old grandfathers hand luggage bag was taken from him at the door of the plane on a Mango flight from JHB to Durban on May 6 2018. To date, the bag cannot be found and Mango have been of no assistance. Only after taking to twitter did I receive one call to say the matter is being dealt with. This was 14 days ago. A month has passed, no trace of the bag and absolutely no communication from Mango airlines except empty promises that my claim will be escalated. Pathetic service from Mango airlines.