We are a small business with 4 phones. We've been a customer since 1990. In the last year two of our phones are charged at a base monthly rate of $47.50, while 2 are now being charged at a rate of $59.00. The plan is the same. This of course does not include add-ons, usage charges or taxes. After hours on the phone with the 'call centre', the best they can offer is that two of the phones had a lower rate associated with new activations. This is not true, all the phones have been active for many years. I'm currently on hour 2 of holding for a 'supervisor'. Not optimistic.
It's tough to offer any insight since there could be a variety of reasons why this is happening and we can't view your bill breakdown and/or your account details. I suspect it could be expired discount codes, though. Did you hear back about it from the support team?