According to the product page (in the What's in the Box section) the dimensions are stated as being 2.82 x 2.67 x 3.47 inches. Presumably the height is 3.47 inches. It would be odd for the model to be smaller than what is listed although it could happen if:
1) Shapeways somehow scaled the part to a different size in the production process. Unlikely for that to happen but that would obviously be their error and should garner a refund.
2) The print is broken in production or during shipping due to poor packaging. That would be obvious. Also probably Shapeways' fault.
3) The shop offered the model in multiple sizes and the wrong size was inadvertently purchased. However at present there is only one model present in this size in that shop. Not sure if they refund for this scenario.
4) The shop owner offered a smaller sized model prior to the purchase but altered the size after your purchase, either through a new upload or using the internal Shapeways size scaler available to the designer. In theory Shapeways uses the model shown on the product page at the time of purchase. In this case it also wouldn't be the fault of Shapeways unless they somehow used the wrong model during production.
5) Similar to 4) but the shop owner completely deleted a smaller sized product after the purchase and then uploaded the larger size we see there now.
Customer service should be able to tell which if any of these scenarios happened based on information that is automatically logged by the system such as dates, product and model numbers, etc. The one thing they will probably ask for when they do contact you is a photograph of the print next to a ruler or something to gauge the size to help them troubleshoot the issue. Also take a photo of the sticker on the bag the part arrived in. You might want to take the photos before they get back to you so you have them ready to go.