Pricing vs billing

I was flummoxed by the difference in listed sales price vs billed price. In my bill, the "free" camera was added into the package price. That raised my tax. Then the discount was taken off the package.
When I add the listed sale price and extras, minus camera, plus new tax, my bill should've been $15-something less.

I called and was given the correct pricing reimbursement.

I hope it's not an intentional bill issue, just an oversight.
Regardless, it needs corrected.