Don't receive my parcels

I used to buy stuff on ebay 1 item at a time and then receive it. Then 1day I bought a few items at once to the value of R1200 and i never received it. We go check at the post office regularly and we phone them and they always have excuses to not help us and say it is not there. A few months ago i ordered from wish app and evay again. It was sept 2017. The stuff should have been here by end of nov 2017. We phone weekly for our parcels because somehow the post office doesnt send us that little paper to say there is a parcel and when we go in and ask for out parcels it is never there anymore. We went to the post office again today and they said there is nothing. It might be sent back. It wouldnt be a surprise if they take some parcels and resell it or something coz they know if we tell the suppliers we didnt get the parcels they refund us... most of the time if it is in the period of time they give us.