Any success ? My past few experiences (MBB CC) are all the same, bad and slow.
e.g. 30k CL asking for 5k extra only, CS will say need few days to get approval, in the end rejected. Some didn't bother to get back to me and already past the "emergency usage period needed".

In the end, I use other foreign banks CC, CL increase 10k within 2 hours or sometimes immediate.

There are difference between:
1) Online transactions with overseas payment gateway.
2) Physically overseas to swipe physically there.

I believe your problem is #1, MBB will require you to swipe, then call CS and they can see the transaction request comes in, then approve it. Then you online transact again with them on the line.
If call disconnect, try again.

If #2, always make it a practise to call MBB when you are at KLIA departure hall to inform the period you will be overseas, which countries, etc. Add a few more days at the end, in case flight delay/natural disaster/etc that you get stuck overseas and need to spend for hotel/food.