Hospital managers in Lincolnshire say they are sticking with a controversial increase in parking charges.
The increases at Lincoln, Boston and Grantham hospitals have caused outrage from patients since they were introduced a week ago.
Administrators say shoppers are abusing the car parking facilities and running them was a drain on funds.
But Lincolnshire's Patient Forum says a compromise needs to be found and has written to the trust about the charges.
Daily charges have risen from a typical £2 to £3, and a charge of £10 has been introduced for long stays.