Can't get help with billing questions

We switched our service from just a regular Comcast account with 2 lines to a Comcast Business account with 3 lines and a new expensive phone system!  We are now receiving TWO bills - one for our new Comcast Business account, which looks to be correct except for the fact that it does not include our internet service, and a second bill on our OLD account number which is for our internet service and something called Comcast Digital Voice (have no idea why we need this on a separate account when we have everything included on the Comcast Business account).  I called the business office and spent 30 minutes explaining the situation to a rep who said she could remove the Digital Voice charge from my OLD bill, BUT then she transferred me to another rep who wanted me to go through the whole story again.  I am trying to run a business and I don't have hours to spend explaining the mess to several different reps!  I have been trying for two weeks to get the salesperson who sold me the new system to get this mess straight, but I haven't gotten very far with him either.  Yesterday he promised to call back by the end of the day and he STILL has not called.  Both bills are due and I fear if I pay them as they are now I will have h___ to pay trying to get a refund.  Which way should I go now???