Following a VOSA-led investigation, Darley Ford Transport (HGV) and Darley Ford Travel (PSV) have been fined £50,000 for driver's hours offences.
The Liskeard-based operators were also ordered to pay costs of £11,470.
Ten drivers were also fined a total of £3,530 for driver's hours offences – including taking insufficient rest, exceeding the 4.5 driver's hours rule, false records and failure to use a tachograph.
They were also ordered to pay £3,482 costs. Another six drivers were disqualified from driving for between 10 and 56 days.
"VOSA's number one priority is road safety, and investigators will always seek to prosecute those who risk the lives of other road users through arrogance and ignoring the rules," comments Heather Cruickshank, VOSA's operations director.