On the first post, there is an appeal letter, you may use that sample. Courtesy tifosi.
This card has rejected too many of us, until an appeal letter needs to be attached on this thread.

I'm not sure if they still accept appeal these days, I hope yes, else you have to reapply again.

how much ur salary?

i found that those online applications will get rejected most of the times.
i have been rejected 1 time for using online application.
then someone advised me to apply at the branch instead of going online, those telesales may not submit your forms accordingly.
after they rejected my application, 1 month later i went to the branch, this time they approved my application.
since then, i never trust those telesales anymore.

Usually if you don't have any credit history before, OCBC may reject you straightaway.
This is based on the experiences shared by few forummers here.
Try to get other banks' cards first before applying, that also doesn't guarantee you won't be rejected. I'm one of them.
But at least the chances to be approved later is higher, that's based on my own experience. I have 2 cards before applied for OCBC.