Worst service ever

So my screen was sent in for repairs over 8 months ago, the consultant assured me they would back up all my data. This of course was not done, lost hundreds of sentimental data that i can never get back. The rude and *****y consultant did not care and my emailed complaint has not received any response or outcome since this time.....8 months ago.....complained on Facebook, was told to send an email to specified email 2 months ago, no response......where do i go from here to get some sort of answer????