Mont. Code Ann. § 80-4-524

A warehouse operator may not directly or indirectly, by a special charge, rebate, drawback, or other device, collect from any person a greater or lesser compensation for any service rendered in the storage, conditioning, handling, or shipment of agricultural commodities than the operator collects from any other person for a similar circumstance or condition. A warehouse operator may not make or give any advantage to any person, company, or corporation or subject any person, company, or corporation to any undue or unreasonable prejudice or disadvantage.