Did you have a verified income statement from your embassy in Bangkok? Which immigration is not accepting this statement. Yes i know a few friends use this way yearly . Their embassy provides a verified income statement. And the immigration is Bangkok and Chiang Mai
You probably had something wrong. Might not have the 40K certified by your embassy in Bangkok. Many countries not provide income certificates anymore and then its 400k on the bank only.
In case of having any other income from abroad such as pensionLetter from the applicant’s Embassy in Bangkok verified his monthly pension or other income not less than 40,000 baht