A terrible experience and no way to treat any supporter, let alone someone of your age and time put in.
Sounds like a right prick this person.
Don't give this jobsworth the satisfaction of ending your journey with City, although I do get the various hurdles and pathetic customer service which I have also encountered this season.
I also wore smart dress shorts that day, but I had a ticket for 93:20, and I'd have told them to get to fuck.
If nothing else, ask for a refund on the pants you were told to purchase, the embarrassment you were caused.