Billing and being harassed about the previous tenants debt

Signed up for Xfinity Internet services and they were initially nice. Applied for the services at my sons old address where I now live temporarily  until I find a new place. They informed me that he had previous debt and they were well aware we were separate households.   I set my bill to auto payment and when the first bill was due and the payment was processing they shut off my Internet. I called in and they said they are aware that it was the previous tenants debt but would stall my service until I payed his debt it's ridiculous that I should be responsible for his debt.