Mercantile Adjustment Bureau, LLC | 408 followers on LinkedIn. Mercantile was founded in 1934 as an accounts receivable management firm servicing Western New York healthcare providers. While remaining loyal to the healthcare business that gave us our start, Mercantile has significantly diversified the services we offer, as well as the local and nationally renowned client base we service. As a result of strategic changes, restructuring of the Company’s infrastructure, strong organic growth, significant capital investment and selective acquisitions, Mercantile is recognized as one of the ARM and Call Center Industry’s leading companies.