Does this phrase make sense here?

Question

When the client feels the invoice isn’t fair enough for the quality of design:.

In the above sentence, I used the word fair for invoice. Basically I want to say that the client feels the quality of design isn't good and still he has been given an invoice with more charges/bill (sorry I don't know correct word).

I Googled the similar use of fair invoice, but couldn't find satisfactory results. I understand the meaning of fair bill, fair deal, fair commenet/question/answer etc. But I just can't say about this use.

So the fair enough for phrase makes sense here?

Answer 1

That would more likely be said simply "isn't fair", maybe like this:

The invoice isn't fair given the substandard quality of the design.

You might also just say

The invoiced amount is excessive for such a low-quality design.

"Not fair enough" doesn't quite work.