I know that universities look pretty dimly on those companies as being somewhere beyond the fine line between teaching and doing the job for someone. If you want to genuinely get help with where you're having issues, I would try some private tuition so that you build your confidence/abilities, etc and are equipped to solve the problem if/when it arises in the future by yourself. A private tutor isn't that expensive these days - if you try the link I've given you that should give you an idea of costs, etc.