I called back number (02) 8326 9100 reached IVR for a company called American Express.

Caller: American Express

American Express call center requesting you to provide identifications extremely useful for spammers. Dont provide any identification and black list this number.

They called twice and remained silent before hanging up.

Caller: American Express

A payment I made bounced back to my account.

American Express called to advise me of this to avoid any overdue fees etc.

called 5 times in one day and multiple times through a week period. no messages left on message bank. unknown numbers i leave to go through to message back.

Called multiple times. Said they were from American Express and needed to verify my details - date of birth etc. I declined to offer personal details over the phone and they requested that I called Amex back. Very suspicious.

AMEX confirmed this is from the travel section when you have made a booking for accommodation or a flight
The way the number operates is ridiculous. You cant call the number is gives you 2 different numbers for other options and then hangs up
This number is for outgoing calls only
I have told AMEX it is not good for them to operate this way

Caller: unknown repeat caller

repeat caller without message provided. This type of call 'skimming' is increasing so beware of who calls, what they ask and why they call you unsolicited.

They called 4 times. On all occasions I heard automated "Will you accep..... " a click, then silence for 30 seconds each time before they hung up.

Answered call, then after a couple of seconds a computer voice says "to accept....." then voice stops and there is silence. On the 3rd call I did not hang up and waited but no further speak and after 30 seconds the caller hung up.

Same thing: ring and hang up

They called twice. On both occasions I heard automated "Will you accept th..... " a click, then silence before hanging up.

personal feeling it is called from Chinese CCP

Caller remained silent and hung up as soon as phone answered

I get calls at my work place at least 3-4 times a day from this number
Noone speaks just hangs up

They called twice this morning and remained silent before hanging up.