(a) A person who violates this subtitle by contracting for, charging, or receiving interest or time price differential that in an aggregate amount exceeds twice the total amount of interest or time price differential authorized by this subtitle is liable to the obligor as an additional penalty for all principal or principal balance, as well as all interest or time price differential.
(b) A person who is liable under Subsection (a) is also liable for reasonable attorney's fees incurred by the obligor in enforcing this section.