I'm assuming you mean a 12" long piece of rebar and not a 12" wide piece. This is not likely to give you the results that you are looking for. Did your contractor explain the causes of foundation failure and specifically how his "system" is going to alleviate the cause of the problem? What sort of warranty did he offer you? There are many different solutions to a bowing wall problem. Some work better than others, some don't work at all. From the information you have put on here, it looks like yours is the latter. The best advice I could give you is to find a contractor who is a member of the Basement Health Organization and specializes in the restoration of the structural integrity of a failing foundation. Where are you located?