Being nice

I joined a team that will provide consulting services for a project somewhere in the Southern province of the Philippines. Our group (three of us) was just a support crew to the main consulting group that won the project bidding. As the project rolled on, it happened that our group are now the star players while the two other groups have nothing to show for their own work division. And in our own group, the client goes to me for advise and requests, while my two other groupmates take their time answering the queries and requests. Is it because I am always the "nice" one to people?Why can my two other group mates afford to look the other way when the client is requesting for things to be done. I do not have the heart to let a client wait. Maybe, that is what is wrong with me, I am too nice to a fault. That clients and friends are already abusing me and has taken me for granted. Maybe I am always available. Maybe I should learn a thing or two from my other group mates who don't care and will deliver the work product on their own time. I should stop caring.