I am going to send them this and see what happens

Athena ANPR
(Copy to Lidl Customer Services)
4th December 2014
Dear Sirs,
Ref Parking Charge 0 0001 749 211 2nd December 2014
Further to your parking charge, please be advised that I have parked and shopped many times at the Barnsley Lidl when the free parking period was an hour (possibly two) and I was unaware that this had changed.
Now this change has been brought to my attention, I will of course abide by your parking rules in future.
The fee of £90 (reduced to £45 for early payment) for twenty minutes parking is unacceptably high, and completely disproportionate to any cost incurred by my parking.
Furthermore, I do not agree I have entered into a contract and intend to challenge this in court if necessary.
As a gesture of good will but with no admission of liability, I am prepared to pay a reasonable parking fee for the additional ten minutes of parking mentioned in your letter and enclose a cheque of £1 which I consider to be more then adequate.
Yours Faithfully