You can upgrade in the program & you will only pay the difference of what the higher version cost.

How do I upgrade my TurboTax for Windows software?

https://ttlc.intuit.com/community/upgrading/help/how-do-i-upgrade-my-turbotax-for-windows-software/0...

How do I upgrade or switch to a higher version of TurboTax Online?

https://ttlc.intuit.com/community/upgrading/help/how-do-i-upgrade-or-switch-to-a-higher-version-of-t...

If you already purchased the Self Employed version without upgrading, you would need to contact TurboTax support for a refund.  In the box What do you need help with?, do not put refund, entering something like Billing issues.

https://support.turbotax.intuit.com/contact/