HM office lost neutralisation certificate?

Hi, I posted my documents this weekend, yesterday I received an email saying that the documents were received, then later on another email saying that I haven't included my naturalisation certificate. Of course, I made sure to include everything, so I am not sure why they sent me the email. Either they have lost my document or the system is broken, my status on the website says Documents Received, but nothing about missing documents. Did anyone here have a similar situation? I already gave them a call and raised an enquiry, I really hope they have my document. Thanks