dataContractSerializer Customization

<GetBalance 
xmlns=http://ift.tt/1HHKTRJ 
xmlns:i="http://ift.tt/1m4M9U6;
<Credential xmlns:a="http://ift.tt/1HHKTRL;
<a:Password>asdasd</a:Password><a:Username>zxczxc</a:Username></Credential></GetBalance>

how can get this like below format ?;

<GetBalance 
xmlns="qwerty" 
xmlns:i="http://ift.tt/1m4M9U6;
<Credential><Password>asdasd</Password><Username>zxczxc</Username></Credential></GetBalance>