Not every win is worth the same. Premier adjusts your CS Rating after each match based on the result and on the rating of your opponents compared with yours. A win against a stronger team lifts you more than a win against a weaker one, which is why the same number of wins can move two accounts by different amounts.
That is also why we do not promise a fixed rating per win. What you buy is the wins themselves, played by an experienced booster who aims for convincing scorelines rather than close finishes. In practice, a series of clean wins is the most reliable way to push the rating up and to reach the next colour band.
Premier groups ratings into colour bands: grey below 5,000, then light blue, blue, purple, pink and red every 5,000 points, and gold from 30,000. A few wins near the top of a band are often all it takes to cross into the next one. If you are close to a new colour, mention it in the request and boosters will tell you in their offers how many wins they would suggest.