Even if you had gotten the tourist visa, you would have been denied entry again by land and air. So please do not try to get in via Nong Khai, you will 100% get denied (even without the denial entry, you would be denied).
You have a denied entry in your passport, which will be more costly to get back in. Please contact a reputable agent like
The money need to be in the account for several months. You can't just put the money there and they issue the letter. This is in response to a scandal with Chinese getting scams.
Because you asked for 30 days when 30 days is not a thing. It doesn't exist. It's 60 days. So they can't give you something that doesn't exist. They laughed likely because with your travel history you should know better. The 60 days visa exempt replaced the 30 days a while ago.