Air Arabia / lies of lost luggage

I flew from Morocco to Barcelona on the 15th of June 2018. I am still without my luggage.
PNR No: 15BJ1V SEQ/120 Flight No:30 373

I spoke to the person in change at BCN airport, who told me that the luggage was left in Morocco and is there along with 2 other pieces of luggage from someone else on the flight. He gave me the paper and said the case will be sent in a taxi to my flat in BCN by Monday. This never arrived with now calls or assistant or reassurance. Finally some weeks later this is not true and Air Arabia have now lost my luggage and I will not be getting it back. I was told to send all my paper work via recorded delivery with an address to send it (2 different ones) I sent a further email as they were refusing to answer any of my questions or concerns and I explained that I had a word of sending my original paper work, since I didnt believe or have the confidence in the company that I will ever see it again and I am sure I will have problems. They told me not at all and to send it recorded to avoid problems. I did so and then had to email several times again and now they're telling me that I didn't send all the documents and without it they won't pay out. I posted everything as they asked and now still have further problems and I don't know who to turn to regarding my belongings. I have lost everything in that case. I am a designer and I have lost all of my own pieces that can never be returned. They are treating this case with no care at all. I am so upset and disgusted. Can you please help me to understand why you have staff that would do this?

Please be assured that I posted everything that you required of me and did so very nervously and with every right to be after the customer service this airline is giving me.

Kind regards
Karina