LG fairprice competition

I won an LG competition from fairprice but the manager from Protea Glen ext 11 refused to help me when i went to collect the voucher that Mohammed from fairprice head office who's in charge of the competition said i should collect my voucher from the store were i purchased my LG product , they took my details and promised to call but up to this day I'm still waiting for their call, when i purchased my goods they showed good interest because i was using my money but now that i have won an LG R5000 voucher they don't want to help me.