I have been a customer of Fibertel for my broadband needs for several years. Their service has not sucked bad, even if I had a few problems in the past.
However, a month ago, I decided to switch to a competing service for a good reason: it's much much much cheaper 
Since I am not stupid, I canceled late with Fibertel, so I would have a full month of overlapping service. I thought hey, maybe I would come back if the new service sucks 
What happened next has been increasingly annoying.
First Fibertel called the person who contracted the service (not me). That's reasonable.
Then they called me to ask me why I was cancelling. I exlained that the other service is (all things considered) about 75% cheaper for the same performance. I suppose that's reasonable too.
What started becoming less and less reasonable are the next 5 calls, each offering cheaper rates, but still more expensive than my new service.
What was not reasonable was that they started calling to tell me technically unsound bullshit to scare me into their service again.
What is definitely not reasonable is that they called me 6 times, even after I told them to stop calling me in the third call.
What is incredibly stupid and annoying was that they decided to block my internet access in order to show me an ad about the same offers I ALREADY DECLINED and until I clicked that ad I could not use the Internet.
What is freaking nuts is that because I have an access point I couldn't see the satan-damned ad, so I was left without internet until:
I removed the access point
Hooked my notebook to the cable modem
Got rejected by it
Hooked back the AP
Got the MAC from it
Faked my notebooks MAC
Clicked the Cthulhu-pissed ads
Hooked back the AP
Un-faked my MAC
So, I needed to spend an hour doing this.
Therefore, dear Fibertel, your company also provides cable TV. I am pissed at you. I have decided to buy service from DirecTV exclusively to piss you off.
Yup, I, who have been paying you every month $230 for years, will pay you $0 next month. I could have paid you $100, but no, you had to be asses about it. You couldn't let me go. Well, I do not like being pestered. I do not like that you acted like a spurned 17-year old 
Fibertel, I kinda liked you, but my opinion of you has gone lower.
Also, any Fibertel customers out there: if you ask to cancel the service saying you switch because of the price, they will offer you 3Mbps for a year for $79. If you say no, they will offer you 3 free months.
That's a $600 saving, so go ahead and take their money.