Persistence.... started off with the same "reason" you were rejected [yes, our circumstances have clearly been omitted in error and it really is astounding that the Branch staff are seemingly unable to recognise that, and act logically .... I had the same problem when I wanted to open a joint K-Bank Account with my wife - despite being a long term customer with a couple of current accounts, my request was initially declined by Ban Phe Branch even though both of us had accounts there. It's absolute madness that was only corrected after I directly emailed KBank HQ].
As for the SCB EZ Account, after they checked a couple of times with their HQ, they finally agreed to let me open two Accounts (Savings Account and the EZ -my 1st ones with SCB) - after approval, I had a few more wasted visits due to administrative deficiencies at the Branch (a suspicious person might think these impediments were deliberate...). For this pig-head, it was a matter of principle to eventually succeed.
Chok Dee