Don't forget your 180 days has a 90 day report to immigration. The stickers you see isn't the stamp it's a physical copy of the visa from someone doing on person not evisa, but they are the same.
If you have been in thailand for awhile before applying some embassies are not only asking for the 500k statement but they want to know where the money came from. Need to show deposits or withdrawals from outside of thailand especially if using a thai bank account. Even under soft power they can ask about your employment and ability to support yourself without working in thailand so bring as much documentation as possible.
What did you bring in addition to your visa? Did you bring a certificate of residence or any other supporting documents? 3 banks isn't alot of tries either. Same bank different branch may yield better results. Dress well and bring as much supporting documents like residence certificate, house lease, thai license etc.
Thailand also has a basic multi entry tourist visa you can apply for easily. You get 60 day stamp everytime you enter and can extend 30 days for 90, then need a border bounce or trip. If you get a 60 day stamp just before end date of the visa you can get almost 9 months