Mo. Rev. Stat. § 408.236: Recovery of interest barred, when, exceptions — actions taken or omitted in reliance on interpretation by division of finance, effect.

Any person violating the provisions of sections 408.231 to 408.241 shall be barred from recovery of any interest on the contract, except where such violations occurred either:

(1) As a result of an accidental and bona fide error of computation; or

(2) As a result of any acts done or omitted in reliance on a written interpretation of the provisions of sections 408.231 to 408.241 by the division of finance.