In this particular case, I must admit I like blaming technology; in this case, e-mail.
It's a kind of white-lie, but has the advantage of:
- Leaving you blameless: you cannot react to something you didn't receive.
- Leaving an out to the other party; not a particularly elegant out, but better than to corner them and have them resent you.
Once the "excuse" is in, then move back to business immediately.
Example of reply:
Or whatever form of address is in use in your company.
CC your manager. You are in "hot potato" mode, so they are too. They may be asked about it, so from now on keep them in CC for all further developments, that they stay on top of the situation.
I double-checked my spam folder but could not find any notification that the provided data was either incomplete or limited; nor any request for further samples. If you give me the name and date of whoever sent the feedback, I'll make sure the IT team investigates and resolves the issue.
I would not expect that anyone steps forward and announce they sent an e-mail that they actually didn't, nor that anyone would denounce a colleague. It's expected they'll keep silent and nothing further will be said. If they do send a name, then do follow through and ask the IT team to investigate; who knows, it may be genuine!
In the mean-time, I'll call to clarify exactly how the samples provided were lacking and make sure that we agree on what good samples are, then send a new pack of samples.
Move back to business immediately; it'll take precedence over the "small" issue above and avoid awkwardness. It's time to show that you are pro-active, and will get issues solved. Since asynchronous communication failed, move to synchronous communication: either call or drop by their desk. If they cannot accommodate, schedule a meeting (call or physical).
-- signature --
Finish with all the right forms.
You'll want to leave a trace, that they cannot shift the blame on you a second time, so once you have collected the (objective!) requirements, immediately mail them to the group. Once again, CC your manager.
Go ahead, and collect the new samples, make sure they do pass the requirements specified. Send them by e-mail, CC your manager.
And finally, after 2 days without hearing about the quality of the samples, double-check with them. A quick call, or dropping by their desk: "Did you receive XXX? Are they good enough?" ... then reply to the e-mail in which you sent the samples, and document the reply "Hi X, as discussed, please do let me know about any feedback you have once you have checked the samples."1 or "Hi, X confirmed that the samples look good. Please let me know otherwise."
And that's it for now.
Do be careful with this team in the future, though. If they are trying to shift the blame on you for being late, they may find other convenient excuses. So keep documenting everything in the future.
1 Whether you check a second time is up to you; I wouldn't, unless asked to by my manager.
I used to work in a very big company, and while most people I had the chance to work with were professional... a few would always try to shift the blame to someone else. The first time it fell on me, I was quite surprised. I did learn an important lesson though: be unfailingly polite and comprehensive, offer outs, but document everything.
I still remember a few years later, when working on a time-sensitive project, when during one of the monthly meeting with the project director, a team leader (from another team) blamed me for his team lack of progress, live! The sensation of everyone in the room suddenly jolting awake to look at you is really unnerving. The look of embarrassment on the face of said team leader when I checked my notes and announced I had done my part -- on time -- and sent him an e-mail 2 or 3 days prior was quite rewarding. The way he shriveled when the project director pounced on him asking how he could have missed this e-mail, and the sermon that ensued, was awkward admittedly... but he never ever tried to shift the blame on me afterward.