So praying DOES banish bad luck if you ask for banishing bad luck?
In my opinion we often create our own "bad luck". It isn't so much that it is bad luck as it is the result of our choices of actions that have unforeseen consequences. So it is always wise to look carefully at our choices and our actions to see if there is the possibility of unsatisfactory outcomes from them and then take care not to repeat those actions.
Prayer can't hurt in trying to reverse what has been happening to you, and it may in fact help. But there are no promises there. Remember the story of Job in the Bible? He also had lots of "bad luck" and he berated God about it. It wasn't until he realized that his bad luck was God's way of telling him he was making poor choices in his life that he was able to reverse his fortunes. Up until that point his prayers were not getting him what he wanted. Prayers don't always work.
For that matter, magic doesn't always work. Just like with prayer, magic isn't going to change your luck if you keep doing the sorts of things that brought that "luck" in the first place. All change has to start from within.