"Car parking."

Why do you have Pay and Display car parks?

We had a pre assessment appointment at 15:30. We arrived at 15:10 but had no idea how long we would need. I called the reception to ask and they said 1 hour 30 minutes should be more then enough. I bought a 2 hour ticket for the extortionate price of £4.60. The clinic was running late and I then had to purchase an additional ticket at £2.60 to prevent a penalty notice. Why is this?

How can we know how long we will need and surely if the clinic is running late it is not our fault.