The printing color is not close to the artwork i provided.

Sorry for the color difference between printing sheet and the artwork. As you might know, the printing color will not match 100% compared with artwork in computer, because the printing color will be affected by different paper materials. 
As there's no real sample or color proof for reference, we will judge the saturation of the color according to the CMYK value of the document during printing process. 
So if you have strict requirement for the printing color, it'll be helpful if you can send us the real sample or color proof or pantone# to follow the colors while printing. If you cannot offer all of these, we can print a digital proof for your approval before printing. Is that okay for you?