I agree durhamjen. I have a friend who I know is a very conscientious and hard worker. Unfortunately her workload was substantially increased, with no extra guidance or support provided. Every time she approached her manager to ask for guidance as to how various duties should be prioritised, the manager offered no solutions and was bad tempered and dismissive, even saying at one stage "Well, that's the job and if you don't like it........" (she didn't finish the sentence but it's pretty obvious what she meant).
In the end, my friend was so stressed that she just gave in her notice. She had joined the organisation as a temp (so they must have been satisfied with her performance to take her on) and had been there for 4 years, with no complaints made against her. Although she had a case for constructive dismissal, she really couldn't afford to risk the, I think, £2,000 or so to lodge a claim and take it to the employment tribunal. Additionally, there is a small risk that the employer can claim costs if the employee is unsuccessful.
I think it's disgraceful. The tribunal already had the power to throw out "vexatious" claims so it seems to me that the main purpose of introducing these charges was to prevent those on low or more moderate earnings from pursuing their cases.