I will never shop at Mediacom again. Hopefully. They do have a monopoly in some areas, though.
When I moved into my first apartment, I got cable internet from Mediacom. Over the phone, they quoted me a monthly price for the first year of service that was $10 lower than the only competitor in town, and stated that they would supply me with a "free" modem (covered by the cost of the installation/start-service fee). Guy comes, sets everything up, etc. Not long after, I get my first monthly bill in the mail - charging me $10 more per month than I was quoted. I call customer service, they said they will look into it and get back to me. A few days later they haven't called back, I call again, rough summary of the conversation: "You overcharged me; I was told X per month" "Well, that's incorrect, we never charge that low." "Well, I was quoted X over the phone" "Well, we will have to review the call and get back to you." They didn't call back when they said they would, so I called again, and finally was told, "Well, we don't normally charge that low, but since our person misquoted it, we will honor the price they gave you. But it's only the one-year promotional price, so it will jump up to $__ after the first year." Fine, ok, they fixed the billing issue for me.
Meanwhile, during the first several months of living there, I kept getting telemarketing phone calls on my cellphone. My plan had limited minutes and, like almost all USA cell phones, incoming calls use up your minutes. I would answer and sometimes they just hung up on me. When I got a live person, they said they were from Mediacom and was I interested in adding cable TV service, phone service, etc. to bundle with my internet and save gobs of money? The first time I said no thanks. The 2nd time, I said no thanks and please don't call again. The third time, same. Now, there is a national Do Not Call list to prevent telemarketers, but businesses that have had an "existing business relationship" with you in the near past are allowed to call you to offer more services. HOWEVER, they ARE required to stop calling you once you specifically request it. So on the 4th call where a live Mediacom person tried to sell me something, I got a bit terse and told them that I had asked repeatedly to be taken off their call list, and that not only was I not going to buy any additional services from them, but that if they called me again I would cancel my internet service AND report them to the BBB and Federal Trade Commission (or whoever it is that regulates telemarketers; I forget now.). They huffily said "fine" and that was the end of it. Aside from occasional outages, I never had problems with them again until I moved in with a friend and had to cancel my service...
I called to cancel. Reason: moving. "Do you want to transfer service to a new address?" "No." They said they would stop service on the date I requested, and they issue a check for the amount I was due back (I paid each month in advance, and had already been automatically billed for the full month). They told me the exact amount that it would be made out for, and how many weeks before it would arrive. They even asked for (and I gave them) the address I was moving to that they should send the check to.
A week after the check was supposed to arrive, I called to ask what the status was. They said it would be another X weeks. I waited X weeks and then called again. They said it had already been mailed and should arrive any day. I waited several more days. Then I called them from my computer, with the sound recording feature on, notified them that I was recording the phone call, explained the situation, and again asked when I could expect the check. The woman said that the check had been mailed yesterday and should arrive within 2 weeks. A few days later I received the check, dated and postmarked the day of my last phone call (obviously, they were lying through their teeth each time they said it had already been mailed.)
Next time I moved into my own apartment, we went with CenturyLink (previously Qwest) and aside from them EMAILING things that they said they would MAIL, we have not had any problems.