John,

Nobody will sue unless you do. You lost good money and you were in a position to set a precedence case. see below

Republic v National Transport & Safety Authority & 10 others Ex parte James Maina Mugo [2015] eKLR  

Cash is a legitimate, lawfully sanctioned method of payment of any service including transport services. According to him, “cash light” PSV fare payment system is an unconstitutional and unlawful overthrow of the subsisting monetary policy of payment for goods and services in Kenya by means of Kenya’s Constitutionally recognized legal tender

http://kenyalaw.org/caselaw/cases/view/108506/

______________________
Mwendwa Kivuva, Nairobi, Kenya

"There are some men who lift the age they inhabit, till all men walk on higher ground in that lifetime." - Maxwell Anderson