Nonsense. This embassy is located in Europe, so they IF they choose to accept only EUR statements that's fine but they can't also accept USD statements. Also, Thailand uses the Baht, not USD.
I just made an international transfer to a Krungsri account this morning and it went through in seconds. My last transfer to a Bangkok Bank account about 2 weeks ago took 24 hours, normally it goes through in seconds.
If you're in France, why would they accept USD statements? That's ridiculous! If they're not going to accept AUD statements they shouldn't be accepting other foreign currencies either. No one accepts USD in France anyway.
Extend your Cambodian visa! Another option is, cross into Thailand or another country come back to Cambodia with an E category visa, extend that for 6 months and then you'll have plenty of time to apply for your DTV without worrying about your Cambodian visa expiring.
Many times I've entered Thailand where they don't see my visa and incorrectly enter me on visa exempt. I check my stamp and tell them to correct it. It even happens when I put my visa number down on the TM6 form. I wonder whether the new digital form will keep better track.
I therefore assume they can't see the visa on their system unless they notice it in your passport or you hand them the paper in the case of e-visas. I understand extensions of stay are visible in the immigration system because they're issued inside the country.