Contracted for 8 Mailboxes but told I only get 7

I've spent hours with customer service and get the same runaround. My contract with Comcast states I get 8 Mailboxes included with my service. On my account page, it says 8 mailboxes. Currently I have 7 and it shows 0/8 mailboxes remaining and wants to charge me $6.95 for the 8th. The first time I called they "claimed" they pulled my contract and it states 7. I pulled my contract and it states 8. So, I called back in and they basically told me that it's now seven. I told them I wasn't hanging up until I get my 8th mailbox anf that I wanted to be transfered to his manager. They hung up. Has anyone encoundered this issue and what is the solution. If Comcast can void my deal with them, can I void there deal with me?