Well, practically there is nothing better than following it up with the concerned service center. In fact,the actual practice is to send the device without battery for repairs. Whenever, they send your phone for repairs, they usually give the battery back to you and then send it to their repair center. But, since they have replaced the De ice model itself, your case is entirely different. I would advice you to go elsewhere a written complaint at the service center and never forget to get the acknowledgement for the same.
You can write to thir their customer care quoting all your reference numbers. Also find their twitter handles and keep tweeting about your issues. Try shooting mail after mails about the issue.
And if nothing fruitfulness happens even after all these exercises, you can threaten them that you will move consumer forum/court. Ultimately, if all fails consumer forums should be the last resort.