Dear annoying guests:
I am a front desk agent, not a babysitter. It is your job to keep your shrieking brats out of the hotel's mini-mart, not mine. It is also your job to keep them from running off with items from said mini-mart. Perhaps you should teach them the values of good nutrition, rather than constantly buying them candy, chips, and soda. I'm not an expert on children or anything, but I'm fairly sure that high-fat, high-sodium, high-sugar, and high-caffeine snack foods are not terribly beneficial to their tiny biological systems.
Also, keep them off the computer in the business center. It's for guest use, and some guests actually do need to use it for work purposes. They take precedence over your children playing games.