Qatar- No compensation for damaged suitcases

We recently travelled from Durban to Doha. On arrival we reported that all 3 of our suitcases had been broken into. In the presence of a airport staff member we checked all 3 suitcases and nothing was ****** but someone had been through all our luggage. Obviously looking for valuable goods. We have now been advised by Qatar Airlines they will not compensate us due to minimal damage. The one case zip was broken and we could not close. The staff member provided us a large plastic bag so we could put the suitcase in so we could exit the airport. The second case cannot lock now and is also cracked. The third even though broken into we can use an alternative locking mechanism. We have to buy 2 new suitcases but we have been told minimal damage. Very poor service