Refusing Buy.com shipment per their suggestion?

[imagenious]

I ordered a wireless card from Buy.com several days ago and shortly after ordering, I found that the card would not fit system for which it was ordered.

I tried to change/cancel order but Buy.com said it was already in "shipment process". They said:
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We apologize for any inconvenience and offer you three options when your order arrives:
- You may keep the product.
- You may refuse shipment for a full refund, in which case the carrier will return the product to us at our cost.
- If you are unable to refuse the package, you may return the product for a refund. In this case you might not be automatically credited for your shipping costs depending on the condition of the package or when you requested cancellation, etc.

Simply request a Return Merchandise Authorization Number (RMA#) online at https://secure.buy.com/corp/support/login.asp

For more information on our returns procedures: https://secure.buy.com/corp/support/returns
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Order should arrive today and I already have it established with postman to refuse shipment - is that course of action going to be OK?

Anybody ever done this? Would refusing shipment leave a possible issue "open" as to whether or not I receive credit for item being returned to Buy.com?

Thanks for any info offered.