Salary increment!

So is it a pay increment of A or B?

Received letter from GM with regards to pay rise, he actually called earlier to tell me he will be passing me the letter and to keep it confidential.
It was quite funny as he came out of the office with a closed big work diary, with letters in the middle on it. He walked up to me, slightly flipped over the cover, locate the letter and tried to pass me the letter secretly.
I hurridly took the letter from him and kept it. The scene was hilarious to me hahaha.

2nd increment for this half year. One is end of probation increment and this is the half-yearly pay rise and promotion period.

On looking at the letter, there is some discrepancy on the salary amount.

Previously, before probation ended, my salary is S1. After probation and increment, my salary is S2. The letter wrote that I be having a pay rise of A to S3. However, S2 + A is more than S3 but S1 + A = S3.
In short, the increment to my current salary will be higher than the final salary written on the letter. But if the increment is added to my initial salary, then it matches the final salary.
So am I getting a pay rise of A amount (my salary will be more than S3) or actually B amount (which is lesser than A amount) to make it to salary S3?

Will post here once it is sorted out.

edit ~
called HR to ask liao. I email my GM and he say to call HR directly.
Seems like it was a big back mistake! haha. So I will be getting my increment A to get salary S3

woo hoo~!