407.558.  Private civil action against prohibited except if a commercial relationship existed — definition of commercial relationship. — Notwithstanding any other provision of law to the contrary, no person, as defined in section 407.010, may bring a private civil action seeking monetary damages or other relief against any licensed motor vehicle dealer with whom such person did not have a commercial relationship.  For purposes of this section, "commercial relationship" shall mean a relationship between a person and a licensed motor vehicle dealer which thereby directly results in the retail sale or lease of a motor vehicle or other related merchandise from that motor vehicle dealer to the retail purchaser or lessee but shall not include any motor vehicle dealer in the chain of commerce with whom the purchaser or lessee did not directly and personally negotiate or communicate.  No provision in this section shall prohibit a person from pursuing against a manufacturer or seller of a new or used automobile any claim not arising under this chapter.