The crucial ingredient in Charter Properties’ successful quest for sanctions from Rockford Mutual Insurance Co. under Section 155 of the Illinois Insurance Code — which provides an extracontractual remedy for “vexatious and unreasonable” delay of payment — was an expert witness who testified the insurer violated an often overlooked regulation on improper claims practices: 50 Ill. Adm. Code 919.50(a)(1).The expert — who took the stand during a bench trial about sanctions after Charter …