Thank you for your response. I believe I lost 3 BG of data storage
When I used the link you gave me to check on the data I currently have, it reads 9.88GB.
However, as you can see on the attached screen shot, I had 12.88 beforehand. I took a picture of the screen before I upgraded to make sure I remember how much GB I had before the upgrade. The promotional referral used to be 1GB, as you can see in the screenshot.
It might be 500MG now, but when it was earned, it was 1GB. Shouldn't I be entitled to that amount?