Minor correction: They should refrain from making up excuses yes however they should consider how they phrase it, for example rather than saying they accidentally deleted 7 days of work due to a mistake they could say unforeseen obstacles occured and then inform the user/customer of a deadline for when it will be fixed at the latest but work hard to solve it beforehand of course the deadline is +1 day more than what they themselves expect it to be at its latest so that its out few days before that deadline. This way they admit to shortcommings but modify the truth and since it came before the final deadline the user smiles and thanks them for hard work. sad but true thats how communication often is towards user/customer