Bad service from installers

Dear multichoice my name is luke williams i have been with you guys for years now ive upgraged to the explora ultra and have xtraview with 2 extra decoders i got a installer to do the upgrade and so far have paid the installer R4500 and still i got no dstv i tried to contact the installer on numerous occassion but he does not answer there names are ferdinand and robert it only worked for abt 4 hours after they left and now it keeps on saying no communication for primary decoder these please i desperately need help as i wasted R4500 and got nothing in return i tried calling and messaging them but they have blocked my number please help i want to take it further and get my money back or the service restored. There cell numbers are *** and ***.my cell number is ***. These guys are ******s and i am really ****ed at them please multichoice help me plzzzz.