Having issue with my answering machine. Someone left a text message on my landline.

Having issue with my answering machine. Someone left a text message on my landline with their cellphone. I can’t get it to go away. I’ve been on the phone with Xfinity for two hours, the first 30 minutes was trying to get through to a representative through AI. Finally, the representative suggested many things to do and nothing worked, that took another 45 minutes. He transferred me to a different area and representative. I was exasperated by then, he was having me do the same tries as the previous representative. My problem with this is I jumped through all of the same hoops as the first spending all of my time waiting for the representative to keep coming back to me, just a guess but they are simultaneously helping many others at the same time. I was extremely frustrated at this point. After 2 hours I gave up and ended the chat.  I tried to upload a picture but would not upload. Photo in first comment.