I suggest that you hand said perpetrator your hoover, mop, broom, window squeegee, oven cleaner, silver polish and all other cleaning parephenalia and suggest that he/she/it do something constructive in recompense for your aggravation. Alternatively - or additionally - they could turn over your veggie garden for the new season (a task well suited to youngsters since requires brawn rather than brains. He/she/it and mama my deny responsibility for mucking up your 'puter, but you are putting them up (putting up with them?) and saving them how much a night over the cost of a local hostelry?

And before setting to work, he/she/it can go out and get you some proper chocolates. KitKats have their place, but they are not potent enough for traumas of this magnitude (like fighting fire with a teacup). For that you need the best and darkest chocolate money can buy (dark chocolate has far more of the compounds that make chocolate and effective mood lifter)...and for it to be really effective, the money should not be yours!