(a) A lien against assessed property and the personal liability of the owner may be enforced by suit in district court. An amount equal to the interest on the assessment and an amount equal to collection expenses, including attorney's fees, are included in the lien and may be recovered.
(b) In a suit brought to enforce an assessment, it is a defense that:
(1) notice of the hearing was not delivered or published in the form or manner required by Section 286.047; or
(2) the amount of the assessment exceeds the estimate given in the notice provided under Section 286.047.