Conformation #N1LD7J leaving Boston and arriving Paris. I paid $12 for a cabin bag online when booking. The confirmation email said “your bag can weigh 10kg” “your oersonalmktem Can weigh 8kg”. At the gate, my personal item and cabin bag weigh 16kg and they tell me I have to pay $90 for overcharge. She takes my bag and tells me to go pay another atrendant. I step out of line and attempt to purchase for $45 online and I am able, because it is within 3 hours of flight time. I tell this to the attendant and she tells me “no, we have a 6 hour policy, even if you purchase online now it is not valid because I can’t see it”. So now I pay $12 + 90 for a bag that should have cost me $45. At minimum, I would like to request the difference refunded to me of $57. Really I should be refunded the $90 because the information provided to me was inaccurate and I would have picked accordingly if the baggage regulations provided on my confirmation were not misleading.