I don't know if this is some sly Verizon thing but I have the unlimited data plan and they have shut off my data because "the data limit you set has been reached".
Did you set a data limit within the phone's Settings? That message sounds like you set a data limit within your phone itself and have reached that limit, and nothing to do with your account. If you open Settings and type data into the search bar > tap Data Limit > is the Set Data Limit slider set to On or Off?
They could also have that much of their high speed hotspot data and only have a little bit left especially if their plan only has 15 GB of LTE high speed hotspot data before the speed is restricted for the remainder of the billing cycle.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Making sure that you are able to use your plan to the fullest is a must. I'd like to help figure this out. To start I would like to gather a few details. What is the exact plan that you are on? What device are you using on this plan (Smartphone, Jetpack)? Have you ever exceeded your data before?