Bruffin,
Interesting post. Just out of interest, were you really only ever 1 minute late and only ever once per week?
I understand that if you've paid thousands over the years, it might seem a bit petty, but I do think you have to see it from the nursery viewpoint. You may have been a couple of minutes late and others perhaps 5 minutes late. Should they charge the other person and not you? Where exactly do you draw the line? As others say, a minute is a minute to you, but if accepted quickly spirals, if not with you,neither other parents and E are issues to do with enough staff for safeguarding, or shortened lunch breaks or staff being late to get their own children.
I actually think it's better for nurseries not to complain, but to just apply the charge that their terms and conditions specify. Parents have agreed to those and it's all in black and white.
They probably didn't reply to you because they were irritated. That's not a good reason for people running a business, but they probably didn't have much to say. Yes you'd spent thousands over the years, but you were still being late and understandably they weren't pleased about it, esp if a weekly occurrence.
I actually think in your situation, I'd have said I'd probably be 5 mins late each week on that day and asked if there was any possibility of having a set extra small payment arranged, rather than the fine or complaining. This would seem fair all round.