damaged good and billing

Good day

I opened an account in october paid my deposit the the item( sunbeam griller) i purchased was not working i reported it since i wasn't around i brought it back mid nov the at the lewis store brackenfell tested it ad the others only to find out none of the grillers were working, they told me that they will contact the supplier since then im still waiting and i pay my installments. i have been trying to find out what's happening they keep on telling me they are waiting from the supplier its been 3 months now waiting . i need the griller and for fact that i'm paying for something that i don't have it is not right. i opened the account at lewis brackenfell please advice what to do now since i have been billed incorrectly here.

Thank you