servant
n
1 person who works in sb else's household for wages, and often for food and lodging 用人; 仆人; 佣人
have/employ a large staff of servants 有[雇用]大批用人.
2 ~ (of sb/sth)
(a) employee, esp a faithful and devoted one 雇员(尤指忠心耿耿的)
a trusted servant of the company 公司里可靠的雇员.
(b) person devoted to sb/sth 忠於某人[某事物]的人
a servant of Jesus Christ, eg a Christian priest 耶稣基督的忠仆(如牧师).
3 (idm 习语) your obedient servant => obedient.
I suggest that we ask users of this machine what they think about it. We can photograph them using it too. Then we can put their comments at the top of the advertisement in big print. We can bring in some humour too. People enjoy reading humorous ads.