Jet Airways — luggage allowance

My husband travelled from jet airways to Chennai from Singapore on the 11th of April 2015 .He had to board domestic flight to Trivandrum for which he paid excess luggage fare within Five hours of travelling domestic. Generally there is a period of 24 hrs before any domestic flight can charge extra luggage allowance .He is a platinum frequent flier with qantas which happens to be a partner flight with jet .But that too is not helpful.Every year it is the same problem with jet .The staff at Trivandrum or Madurai are not aware of any news and bad customer service.