Petition Progressive taxation on financial services

Contractually it is appalling and immoral of the govt to try and renegotiate a contract after it was agreed and someone accepts a job role. The problem is not the bonus but the contract that was given to him.
What is worse is that the discussion can happen with RBS because it was bailed out but not the other banks so you create a two tier system.
Surely the best thing to do is to apply a progressive taxation system on financial services where anything over 'normal' profits starts to get taxed at higher rates. That will help to regulate salaries but most importantly behaviour. The numbers associated with banking and insurance are such that huge profits can be easily made by taking silly risks .