Microsoft Corporation -Xbox Paid for 1600 Microsoft Points, did not receive Internet

A Microsoft 1600 points prepaid card was purchased on 6/7/2011.

The code was entered the same night as the purchase. The 1600 points were not credited to the account.  I tried on 6/8/2011 to redeem the points through the computer and the code had already been redeemed.

The points were not credited to my account.  I contacted customer support and told them my son purchased the card and the points did not credit to our account.  After approximately 9 calls and emails to xbox, I was told that once the points were redeemed that the code couldn't be reused.

I explained the points were not redeemed by me and the points we purchased did not credit to our account.  I emailed the receipt proving we paid for the points and emailed the points history proving we did not get the points.

I was told another person got credit for the points on their account and we were not entitled to the points that we purchased. 

We want what we paid for.  We want our points credited to my sons xbox account.