Sneaky as hell

I should have known something was up when I didn't get any quotations or documentations while we were doing the financial approvals. The offer of purchase was sent behind my back to the finance person. I never saw it. The initial offer on my old car was R135k, then suddenly it changed to R130k with the sweet talk that I got discount on the new car. Now, a month later (after getting my new car) and finally getting documents out of them, I see they've added an Add On product on the deal which cost me R6950 which I'm NEVER GOING TO USE, NOR ASKED FOR. Now I'm said to contact the financial managers? How will/can the financial managers do anything about the fact that the sales person added more products for me to pay. It's all about the more commission for them.