"Really annoyed to receive a parking fine"

After taking a colleague to minor injuries last week, for which the staff were brilliant by the way, I was really annoyed to receive a £70 parking fine today. I didn’t have any money with me, so paid using my phone and bank details to parking eye. We were there for 44 minutes. Even though it said it was set up on my phone, the measly £2 payment wasn’t taken from my bank account and they are now demanding £40 straight away or £70 if I can’t pay quick enough. I have proof that I made a 4 minute call to them but I doubt they will say that is good enough. Really upsetting after doing someone a favour. I feel like they are robbing me!