Letter of Credit Forum

Dear All,

I have received a the following request from our customer in Turkey:

"our customer xxxxxx needs urgently some papers

showing that the last invoice of XX.XX GBP was wrong ,als

documenting this with British Customs"

The chamber of commerce has advised we need to issue a new invoice and ask the customer to destroy the wrong one.

But I suppose our customer is expecting some kind of declaration proving the invoice is incorrect and the declaration should be confirmed/legalasied by officials?

Would you know what declaration it is and how to get it?

Thank you. Any info is appreciated.