You didn’t read or did you ignore the fact that the Embassy says visafee non-refundable.

Even the E-visa website states “Please also note that the visa fees are non-refundable.”

You will be wasting you time trying to appeal.

The embassy has used man hours to read you application, Do you work for free ?

Apply again if it is so important for you to get that visa.

Everybody else can find the place, where you can upload a 3 mb PDF-file to support your application

They could see then your application was so far of, that it would be waste of both your and their time to ask for additional documentation.

Why didn’t you read the Embassy website thoroughly before you applied, then you would know that no reasons will be given in case of rejection, and you are wasting your time to try to get one.

Nor did you follow this group very close, because then you would have known the same facts, and wouldn’t be surprised.

Start by reading your nearest Thai Embassy website, about which visa options you have, including requirements

Where are you getting that impression from ?

Check local Immigration website

First of all, most DTV requirements are embassy specific, so your questions can not be answered until you decide which Embassy to apply at.

Do not change to the inferior DTV tourist visa, from a real long term visa, f.ex. if you have a Thai Bankaccount now, you may be forced to close it on DTV.

Use search to see the Embassy specific requirements.

Read the Embassy website.

Use search to see posts regarding that specific Embassy.