'Very good service. I requested a change in delivery date because there was a change in the service date. You took care of this for me and advised me when it was taken care of.'
'Thank you for your prompt service upon a short notice.'
'Thank you so much for the one time delivery and I really appreciated the flower and plant choices.'
You won't be able to dismiss this by usual means (escape or click button), but you can close it programatically based on user choices or actions.