So, if I understand this correctly you cannot upgrade an Augmentation by paying the difference between the two models. If I have Dermal Plating MK2 and want to change to Mk3, I can’t spend 11,025 credits (the difference in the prices), I have to spend the full 17,975 for Mk3 and the Mk2 gets taken out (not reusable) in the process. Ditto for upgrading a Wyrmling Dragon Gland to a Standard Dragon Gland.
The only exception is a Personal Upgrade, which specifically says you can boost it by paying the difference.
Have I got that right?