She cannot extend a Non Immigrant B visa at the local immigration office. The correct way would be to apply at the local immigration office for an extension to stay based on working, but considering the length of her contract I very much doubt that her company will want to go down that path even if they could meet the criterion. Her only option is to apply for another non imm b single (90 days) which would still leave her short by about a month.
As I understand it the key thing is to prove that the original currency wasn’t Thai baht. Foreign bank/currency transfer bank -> Bangkok bank > destination bank in Thailand. Show a paper trail reflecting this (including purchase of Thai baht) along with transaction statements. Otherwise it does look like an internal transfer.
I was waiting for you to say that 🙂 Robert.. would she not be better off booking a flight to Laos (within the 30 days) and then getting a proper 60 day tourist visa?