Xfinity trying to charge me 200 dollars for forgetting to buy a Travel Pass

On my way to London I stopped at Canada for about 5 hours before getting my next flight. I didn’t realize that I needed a travel pass in Canada as I just quickly read I could use Xfinity mobile abroad BUT didn’t see the with a travel pass. Now I see a 200 dollar bill and they claim they can do nothing about it. I used PAYG for 2 days equivalent to a ten dollar Travel Pass. It is really regrettable as I have been a customer for over a year but this is how they treat customers. If I made to pay this amount that will surely bring an end to my time as an xfinity customer.