Lost jacket in the aircraft

I flew from India to Beunos Aires where in between at Sao paulo airport flight had stopped for technical reason . The maintainence staff had come to clean the air craft . I had kept my jacket on my seat and when i came back it was not there . I informed the crew then and there itself and as I was promised they would be calling me on my hotel number (which never happened ) and will help me finding my jacket . Am still waiting to get back my jacket and an explanation how can you simply pick someone's stuff without informing the aircraft staff .
My flight detail is Qatar Airways - QR 921  Aircraft 77L from Doha , qatar to beunos aires on 23rd june 2012 .
Flight confirmation number is 8FXOPF.
Let me know if any updates are there on the below email addrress provided .

Thanks,

Email : raina.surbhi@gmail.com