Here’s a little formula for refusing a request:
1) Start with a thank you.
2) State that you’d like to help.
3) BRIEFLY explain why you can’t do exactly what they ask.
4) Offer something you CAN do.
5) If applicable, provide information that might help to avoid this problem in the future.
Here’s how it might sound in a personal relationship context:
Thanks for keeping track of what time Suzy needs to be picked up tonight.
I’d love to leave work a little early to get her, and we have that department meeting this afternoon, which usually runs late. I’d hate to keep her waiting in the cold if I can’t get out of here on time.
Would you be willing to pick her up this time? There’s no meeting next Wednesday, so I will make sure to arrange my schedule so I can pick her up then.
Hey, how about if I grab some takeout on my way home tonight so we don’t have to worry about cooking dinner?
Here’s how it might look in a business context:
Thanks for letting me know about the extra data you’d like me to add to the briefing report.
I’d like to turn this around for you as quickly as possible, and I will be out of the office in a training all morning. I will get these revisions integrated and return the report to you by 3 pm at the latest.
I’ll be in training several mornings this week, and will check email during breaks. I will let you know that I’ve received your request and give you a time by which you can expect to receive the revisions. Typically it will be before 4:30 pm.
I appreciate your business, and look forward to hearing about how well your presentation goes!