So, as I understand your narrative, you parked the car on 23rd Feb, and have not been back to it until yesterday 9th March, 2 weeks later. Any reason for not checking on it ? Whilst councils do have a duty to put up suspension signs with the dates of suspension some days in advance, two weeks is well over the normal period given. Of course if you had been away on business or holiday, you could submit reps on that basis, as the car was legally parked when left on the 23rd Feb.