Free Traffic Legal Advice

I started working a new job where usually employees or visitors park in a 4 story building behind the main building of work which has different  floors for different companies and the ground floor of the parking building is visitors only

My car was parked in the visitors ground floor on two occasions and two £60 tickets have been issued to me as a result

My employer told coworkers it would be fine to park here
 

How do I avoid paying this