Unprofessionalism at SA Airlink

I’ve kept quiet for so long hoping my issues would be sorted,In March SA Airlink damage my bag they later on lost it in transition from being fixed.They later on called me to collect a bag from the airport when I got there it was some cheap plastic bag.Its January now 2019 this happened March 2018.Now they say they can only pay me R800.00 according to thier laws what about the value of my bag?This airline has truly mistreated me as I’ve had no correspondence from thier side unless I call or email them.