No ethical worker can guarantee a certain result from spiritual work, because of the principle of free will. While spellwork can influence a situation, it cannot turn someone who is willfully opposed to an outcome into a puppet or bring you an outcome if you are not taking the corresponding real world action.
Think of spellwork being similar to a healthcare provider administering healing. No ethical doctor will ever guarantee a 100% positive outcome. Some health conditions are simple and easy to turn around, others are challenging, and still others may look bleak. Also, as with medicine, you must also consider if your real-world action is supporting your good outcome. A person who has emphysema and continues to smoke will not have the same prognosis as someone who decides to quit smoking, eat healthy and exercise. A good doctor will provide the best possible care for your situation to bring in the outcome you desire, but it also requires that you do some action on your part to support the intention of healing.
Ethical spiritual workers are the same. We can help with the spiritual aspects of your situation, but for the best outcome you should be supporting your spiritual work with real world action. Our approach focuses on both the practical aspects and the spiritual aspects of your life situation. This is why we suggest a reading before single candle spells and require a reading before doing complex candle work. We will take a look at your case, assess whether the outlook is good, workable or if there is little hope for your outcome and suggest both spiritual and practical guidance.  I look at all aspects to see what strategy is best for the situation. This way, I can provide the best possible spiritual work for your highest possible outcome.