Deceptive business practice with rebates, bad customer service

Full Review
I bought a power supply from Radioshack.com for $99, with advertised two $50 rebates. One of the rebate came back denied, and reason was "no signature on the rebate form". I just happened to keep very good documentation, and I made copies of everything. On the copy, it clearly showed a signature on the rebate form. I called the rebate processing company, OnRebate.com, but they only had automated answering. I left a message as well as email, and no response from them. I then emailed Radioshack support, and received no response either (so much for 24 hour process on the web site). I called Radioshack support, and was told that there was nothing they could do about it. Main while, they are still advertising those rebate with this product.
If you see any rebate offer at Radioshack, DO NOT get excited and jump at the chance. Chances are you will never see that rebate money, and they do not even have to give a valid reason. The whole thing was just really bad business practice. I can understand companies that offer rebates, but hoping that not every one would be able to follow the complex instructions (both shipping form and invoice was needed for this one). But giving a invalid reason and refuse to honor the rebate is almost same as stealing from customer.
I had already contacted American Express to dispute the charge. I know that I will never shop at Radioshack in the future, nor would I recommend any friends or family.