The op hasn't mentioned disability, so you may be safe to assume in this case it isn't an issue, but for the other posters who have been quite forceful in their views that a wheelchair and buggy aren't the same, please have a rethink because that's not always true.
had the pushchair been needed because there was a disability there wouldn't have been an issue. Because there is provision for those in wheel chairs.
The Op was escorted off the building, spoken to rudely and not allowed in. Yet she had spoken to someone prior to the event and had a ticket. I wouldn't have packed my buggy up, it wouldn't be possible for me to take the baby out of the buggy, fold it and carry the baby in.
No where did the Op say she was spoken to rudely.
She tried to enter and event with something she wasn't allowed to take in, became emotional as was escorted out.
What else would you like them to do. Carry on doing their job while she stands there telling them they are acting illegally. May be she shouldn't have started throwing around unfounded accusations.
This whole 'push chairs and wheel chairs are/could be the same' is total bollocks.
Because the OP has never said her child is disabled. It's a pushchair.
My mother needs a wheel chair, when we are going places, we do check they are wheel chair accessible. She doesn't have a choice to get out and fold it into a laptop size case.
I am sorry but, to compare the two. Especially when it's not relevant to this OP is wrong in so many ways.