The kind of service Rankedboost performs is often frowned-upon by game devs. Personally, I don't mind it, it's not illegal, it's been done since multiplayer online games started, and sometimes people don't want to grind through ranks.
BUT - Rankedboost are scammers. If you look at their social media pages you will see they often don't provide the paid for service and then ignore messages about them. In my personal experience, I was a booster for them, I did over $150 worth of work and when it came to my payment, they ignored me then removed me as a contact. DO NOT MAKE A PURCHASE OR WORK WITH RANKEDBOOST.