My last call to my ISP, they said they fixed the problem on their end, now it is Thunderbird's problem. I'm skeptical since they admitted they had a problem and they fixed it, but, can anyone help me? 10 days since it quit working!

I have 4 emails in Thunderbird 2 are gmail addresses, they work fine. The other two are with my isp (knology/Wowway). The emails are on the Wowway website, but they don't download to Thunderbird. My server name is imap.mail.wowway.com, my port is port 143, connection security is STARTTLS, and normal password. My last call to my ISP, they said they fixed the problem on their end, now it is Thunderbird's problem. I'm skeptical since they admitted they had a problem and they fixed it, but, can anyone help me? 10 days since it quit working!