title: Update all Tier prices for a product
body: <p>Without directly querying the Magento database. How can i remove all the tier prices for a certain product based on quantity and customer group?</p>
  
  <p>Then add new tier prices for this product.</p>
  
  <p>Example:<br/>
  Remove all tier prices for a product with the SKU: FD001<br/>
  where the customer group id is: 4
  <br/>
  <br/></p>
  
  <p>PHP 5.3
  Magento 1.4.2</p>