Baggage broken into / no compensation or accountability

Took a flight from JHB to CPT on the 4th October. My bag was broken into during presumably at one airport or the other and the integrated lock on the bag was broken as well as the zipper damaged. After hours on the phone mango says they only cover damage to the bag and that locks are not covered. The lock is an integrated part of the bag Mango. Last time I ever use them. In also experienced a 3 hour delay with them on my previous flight with them.