Huge Charge increase on phone bill

I have 3 lines with xfinity on a 3gb plan as the vast majority of the usage is at home via wifi.  One phone was bumped from the wifi on a update from xfinity in May.  Because I used autopay and they only send you one message that you have gone over your limit (thought we had gone over a little bit) the billing went through the roof from less than $100 per month to $1000.  When I saw what was happening I switched over all 3 accounts to unlimited to prevent this but tried to go through your customer service to see what can be done, even if just crediting the account but was informed by the offshore CSR that they could not credit me anything and even though I have had the accounts for almost 10 years they could not do anything for me "because of policy changes".  I worked for xfinity at one time and know that we had the ability to work with customers to help them in cases like this, but if this is the new "no we do not work with our customers policy" it is a bad policy.