What anyone told you they would do is irrelevant.
What the loan papers that you signed say are the real numbers. If you signed and failed to read what you signed, and thus overpay by $4000, then you cheated yourself by not reading the papers and you cannot complain now.
If you received a statement that DIFFERS from your signed papers from the dealer and the loan company, then you do have a valid complaint.
What anyone told you they would do is irrelevant.
What the loan papers that you signed say are the real numbers. If you signed and failed to read what you signed, and thus overpay by $4000, then you cheated yourself by not reading the papers and you cannot complain now.
If you received a statement that DIFFERS from your signed papers from the dealer and the loan company, then you do have a valid complaint.