This has being playing on my mind, would appreciate advice.
I recently started a new hobby. It's quite expensive but good value for the service I'm getting.
I had my second session a couple of days ago (so all quite new) and was rushing to get there. The hobby costs £40 per session but I got confused and thought it was £50. I definitely remember handing over £50 to the person leading the session; they counted it and put it away.
Later that night I was flicking through my emails and saw one from the week before, reminding everyone that the class was £40 (I paid this the week before so not sure why I forgot!).
I immediately let course leader know but they professed ignorance and said they would "let me off this time" and give me the tenner back next time... I know it's my fault for not having counted correctly in the first place but I feel it's pretty poor that they counted the money (definitely saw them do this) and just pocketed the difference. It's actually put me off continuing a bit.