When ording online, My Price should already include your additional credit.
What phone are you looking at? I can check the normal 2yr price to your "My Price".
The $49.99 price includes your upgrade credit. The 2yr pricing right now for the Touch is $99.99 after a $70 MIR. So $169.99 - $70 MIR - $50 Credit= $49.99.
Problem solved.