Office Depot Performance Protection Plan premium not refunded Naperville, Illinois

I bought computer table on 12/31/2011, since table top was made of glass I took Performance protection plan. While I was assembling the the computer table the chrome coating bottom of the table peeled of and the one of the base where the leg suppose to be screwed on to, came off. I called the store and talk to one the employee and explained the problem. She told me to call the 866-540-0013 number on the receipt. I called the number, customer service agent asked some information to register the product. After that, I explained about the problem. She told me to send the table back. She took my email address to send the the return shipping document. I repacked the the product and dropped off at the nearest UPS location on 01/02/2012. The total cast I paid for the table is $168.68(119.99 cost of the table+39.99fo the plan +8.70 tax).  After two weeks on 01/16/2012, I received Office depot Merchandise card not even a check, for $119.99 the price of the table. Next Morning I called to find out why I have not received the full refund. The representative mentioned to me since I have used the plan, I will not get 39.99 refund which I paid  for insurance. I have not used the table not even single day, I have lost 39.99 this is kind of ripoff. I did not understand what is purpose of buying protection plan? I have bought lot of expensive products. I got either replacement or repair. If I decided to return, full refund. Some one need to help to stop this.