Lost parcel by Aramex and zero accountability taken

I have a parcel that was sent via pick n pay Aramex on Saturday 22 December 2018 from Johannesburg to East London. To date I cannot track the parcel and Aramex has taken zero accountability for it. They just tell me they can’t track it and it ends there. I have had zero assistance and I keep hearing the same thing over and over again “we cannot track”. So now I ask them, now that the parcel cannot be track what then? But the question doesn’t get and answer. I am now on the verge of opening a case against them because they lost my valuables but do not want to take accountability for it. I have been waiting for my parcel but nothing has came. I can barely get hold of them on the phone, I hold for hours and everyday is the same thing.