What should a bank letter include for a yearly extension of stay in Thailand?

When applying for a yearly extension of stay in Thailand using the 'Banked amount', it's important to know the specific requirements for the bank letter. You may want to inquire whether the letter should be addressed to a particular individual at the immigration office in Samut Prakan, and if it needs to include personal information, such as your passport number or other identifying details. Additionally, check if there is a standard 'form letter' provided by the Immigration Department to ensure compliance.