Received contarct sim card not working

Good day,<br> i took a tablet for promotion for R79 per month and they delivered a table with sim card and they called me and said my phone will start working with 24hrs and they said they rica my sim card but still my sim card is not working for more than 3 weeks , when i go to telkon store they said my sim card is locked they dont have privilage to access i have to call help desk but when i called help desk they say i should go to telkom store