I can't comment on the price of TurboTax vs other software as I don't have information on other tax software.
Regarding your tax return, it's common for the CRA to make changes to your return that change the amount you owe. You can look at your notice of assessment to see what changes they made.
If you need more assistance please contact our phone support at 1-888-829-8608. They can look at your return with you to see what happened.