You might think that each month's interest is RM183.33 (2.75% x 7 x RM80k / 84m).
So RM2534.58 / RM183.33/m = 13.825m

But this is wrong. The interest is not RM183/m. The loan outstanding amount is falling all the time, and so the interest in RM for each month is also falling.

If you had asked (at the start of the loan) "how much is the interest per month?"
They couldn't have given you that answer (RM183)
Most of the interest charged is allocated to the early months of the loan.
The amount gradually reduces as the loan progresses.

The justification is, most of your instalment payments at the beginning of the loan is used to service the interest. At that point in time, a large portion of the loan is outstanding, so there is a lot of interest being incurred. As you pay off the loan, the outstanding amount reduces, and the monthly interest (which is dependent on the oustanding amount) also reduces.

Use the loan calculator in the link provided by sky. When you type in the numbers and click the calculate button, you will see that on the 84th month, the interest is only about RM4.

The bank isn't trying to cheat you.

BTW: the rebate amount is not discretionary. It's a myth. The bank officer doesn't decide "This guy has a nice face, I'll give him a bigger discount. That one is ugly. Less discount for him". The formula on how to calculate the rebate is fixed. If you'd gone to the bank instead of asking on the phone, they could probably have shown you the table (no promises though, I don't know how different banks operate). What they may have discretion on is waiving part of, or all of, any late interest and penalties you may have incurred in your account.