Besides other red flags (ex. the cool off period starts from the day you do the contract, so when they come to install, usually after 14 days, you are stuck with them if something goes wrong), my main issue is with the services that they are providing, more specifically, with the static IP.

They are using a service Carrier-Grade NAT (or CGN) due to a shortage of IPv4 (in short, 2 or more customers get access to Internet using the same IP) and, because of this, some customers (like me) pay for a service called Static IP (gives you an unique IP address for your internet connection).

On the installation day, I received an email saying that it would take up to 72 hours to get the static IP. After more than a week I received the follow-up email saying that everything is ready.
I had to call them because the service was not working, and they said that, next day, someone from Networks Team would call me to figure out the problems.
The next day came, and nobody rang, so I gave them a call, receiving the same answer.
Yesterday I rang to make a complaint about my issues, and the person from customer service reassured me that, shortly, someone from complaints will call to talk about it.
So far, another day had passed, and nobody bothered to call or to resolve my issue with the service that I paid for.

From my experience, this is a company that just wants to take your money.