I have made the application myself and hope to save about £5k in the process. I completed 3 forms, visa application, sponsors form and an authority for my daughter to receive and deal with any issues. As she is in AU it will hopefully prevent any postal delays although from what I have read on many posts, the whole process is completed on line.
I thought the forms were very straightforward and easy to complete. Perhaps if you think you have a fight on your hands, an agent might be best place to give advice.