im on the $65 per month iPhone 7 plan and even when i dont buy more data my bill is usually around $100. why is that? im not sure if its because of the payments made via credit, debit or charge cards incur a 0.385% (inc GST) payment processing fee.
Those credit card charges and paper bill fees shouldn't amount to much. If you are constantly paying around the $100 mark and it's not from excess data then I would have a good look at your bill as premium service charges or phone numbers that are not within your plan may be causing the problem. Any additional charges should be listed as a separate charge on your bill.
Edit: Another post made think phone insurance if you opted for it would also increase you payments however as I said above it should be listed on your bill.