After you submitted the application you can not do anything to change the application, until the Embassy eventually ask for additional documentation, which by the way, resets the visa processing clock back to zero, and then you should only provide the information the Embassy asks for, and nothing else.
No need to and it has never been the meaning that people should use agents to apply for DTV, hence the rule that you need to stay and apply for DTV only from outside of Thailand.
There is no need to support corruption by using agents, that is a clear goal of the government, in how they made the DTV guidelines.
And a agent can never so it all, since they can not travel to other countries and apply for you.
Take control of your life, and do proper research, then it is very simple to apply.
Start by thoroughly reading Embassy websites for the specific Embassy to apply at, and read the manual in top right corner of the visa application website.
It was a governmental decision to get better control over who has a Thai Bankaccount, in the essens to get better control over money laundering, monkey accounts used for fraud, and other sorts of criminal activity, hence it applies to ALL Thai banks, as a major bank in Thailand, Bangkok bank was amongst the first movers to implement the governmental rules, and therefore they attracted the most attention.
It has now been in action for more than a year, so no need to discuss it further, but you have to acknowledge it as a fact.
DTV has NEVER been eligible for a Thai bankaccount, since it is a tourist visa, and not a proper long term visa for people wanting to live in Thailand.