Lost Baggage

I am extremely appalled by the service this airline has provided me. I landed on the 7th of May through Ethiopian Airlines from Tenerife, Spain to Cape Town, South Africa, only to find that they have lost my luggage! They promised that my luggage got mixed with a different flight would be landing the next day however I was never contacted regarding that. I have extremely expensive items in that suitcase which according to their regulations will either not be compensated for or I will be compensated 20$ per kg. I’m sorry but I refuse to accept that!!! 20$ per kg will never account for the contents that are in that suitcase. I contacted them plenty of times and they promised that they were looking for my bag but it has literally been 3 weeks now and they claim it has been lost and sent me a form to sign and fill out my banking details??? Excuse me are we just going to disregard that those are valuable items???? Some of them irreplaceable. Avoid this airline at all costs!! This is absolutely disgusting!!!!