I work in a company where I enter data manually into a system. I do about 8000-10000 entries per annum (it's about usage of a certain product which is linked to invoice creation). I was informed last week that in the last few months, 3 entries were incorrectly entered (though the have been corrected after the customer complained), all invoices had been corrected. I have been told that is is an unacceptable standard of working and I am having an urgent meeting with my line manager about it next Monday to discuss my poor performance. I have been in my job for 5 years but I worry I will let go. There were innocent mistakes. Not sure how they happened, just human nature. It's the first time in 5 years such a mistake has been flagged to but I am absolutely terrified as I have now a (disciplinary?) meeting about it. Any advice on how to respond? I am not in a union.