I am confused on using "act for/on behalf of someone".
What is the difference between "The law firm acts for me in this legal action" and "The law firm is acting for me in this legal action". I have found that both may mean that "currently the law firm is acting for me" rather than "usually the law firm acts for me".
For example: After the hearing, Holt, who acts for the twins, said: ‘The award will make a very significant difference to the twins' quality of life. (from https://en.oxforddictionaries.com/definition/act)
A Dublin-based firm of solicitors are acting on behalf of the parents of over 100 children with autism. (from https://en.oxforddictionaries.com/definition/act)
Thanks for your help in advance.