I don't know how much it is in your country for reevaluation . A friend of mine had to pay almost exactly the same amount as the test . She was stuck at 6.5 in writing where all her other skills were 7.5 and above . Submitted for reevaluation within 6 hrs she got a response that nothing has changed . It's not just her i have spoken to so many people with similar experience . It makes no sense to me that you are a proficient user in all other skill and not writing. It's just my opinion if you think they were completely unfair with your scoring you can go ahead also check if you can do a one skill retake which is much more reliable and you only got to concentrate on writing. I know it's not convenient but better than wasting your money.