Am I responsible for this?

My roommate moved out during June, during that my gf (who she was friends with at the time) was moving in and had asked for the information for utilities to switch it over, in which she received no response. As soon as rent was paid for June I had asked the landlord regarding the utilities (for July and on) and he had said she would need to do a transfer to our names, or she’d need to cancel it completely. So after that I messaged her asking for the information again and told her that the only other way would be to transfer it. (She was more than welcome to cancel it by that point so even tho there’d be no power at least a couple days there’s the opportunity to fully change it).

There has yet to be a response and we’ve yet to receive a mail bill.

At this point if she hasn’t called to have anything changed would she be responsible to pay?

We have been more than willing to pay but she does not want to answer. I am trying to avoid a major bill.