Parkign Eye review: Unjustified parking charge multiple times from parking eye

I parked for 51 minutes in Aldi at Dartford where 90 minutes is free parking which is clearly signposted. There is no system of entering registration number. I received a penalty notice a week later! This is not the first time, it is fourth times, it is another in a history of the same unjustified action against me. I now believe, as do others, that Parking Eye randomly send out these penalty notices hoping that customers will just pay the £45.00 reduced charge. Is there anyway to penalise the company for unnecessary hurdles given to the customers.