I hate to break the news to you...your belly may stay saggy no matter how much toning you do.
I'm not saying it's a certainty just a possiblity. Stretched skin can take some time to tighten up or may never recover. I have massives of loose skin (losing 87 kilos will do that) that I know will not tone up no matter how hard I try. I wear it as a badge of honour and a reminder not to put the weight back on.
It's a vanity thing anyway...in the end we all go wrinkly no matter how hard we try.
The ab twist wont do it...save your money.