念のためにお尋ねしますが ……
Nen no tame ni otazune shimasu ga …
Just to make sure I’ve got this right …

There’s never any harm in making sure. When you receive important information or instructions, it makes good sense to go over the essential points twice, even if you’re pretty sure you got it right the first time. There’s a ready-made phrase for this purpose:

念のためにお尋ねしますが ……
Nen no tame ni otazune shimasu ga …
Just to make sure I’ve got this right …

It’s particularly important to get repeat confirmation on easy-to-confuse items such as names, telephone numbers, dates and times, and figures and amounts—in fact, it’s a cardinal rule of business. Here’s how it’s done:

念のためにお尋ねしますが、新宿支店ではなく新橋支店ですね。
Nen no tame ni otazune shimasu ga, Shinjuku shiten de wa naku Shinbashi shiten desu ne.
Just to make sure I’ve got this right, it’s the Shinbashi branch and not the Shinjuku branch, right?

or

念のためにお尋ねしますが、田中さんに電話すればよろしいんですね。
Nen no tame ni otazune shimasu ga, Tanaka-san ni denwa sureba yoroshii n’ desu ne.
Just to make sure I’ve got it straight, it’s Ms. Tanaka I’m supposed to call, right?

This is also a useful tactic to employ when you’re told something that doesn’t seem quite right. Maybe the other person misspoke or maybe you didn’t hear what you thought you heard; in any case, you can put your doubts to rest by requesting confirmation. For instance:

念のためにお尋ねしますが、電話には私どもの前川がでたんですね。
Nen no tame ni otazune shimasu ga, denwa ni wa watakushi-domo no Maekawa ga deta n’ desu ne?
Just to make sure I’ve understood, it was Mr. Maekawa from our staff who spoke to you on the phone, is that correct?

念のためにお尋ねしますが、お買いもとめになったのは3月23日ですね。
Nen no tame ni otazune shimasu ga, okaimotome ni natta no wa sangatsu nijuusan-nichi desu ne.
Just to make certain, the date of purchase was March 23, is that correct?

When you’re speaking to a valued customer, even if what she’s told you is utterly implausible (Mr. Maekawa retired two years ago and the store was closed for a national holiday on March 23), you can’t afford to alienate her by directly contradicting her version of events. By leading her through the doubtful details a second time, you can give her a chance to correct her own mistakes without having to offend her by pointing them out. Still, if she sticks to her dubious story, you may have to gently point out the inconsistencies. You can use one of these phrases to broach the issue:

私の思い違いかもしれませんが ……
Watakushi no omoichigai ka mo shiremasen ga …
It may be that I’m mistaken, but …

ちょっと気になる点があるのですが ……
Chotto ki ni naru ten ga aru no desu ga …
There’s one point that seems a bit curious …

– Source: A handbook of common Japanese phrases –