True. I guess it probably depends on the Bank. I had a Texan friend MHRIP and he had to have his pensions paid into a US Bank etc as they wouldn't send it to Thailand.
There has to be clear evidence of a relationship, ie marriage certificate and pictures over a period of time. Evidence that she will return to Thailand, ie job, children, property. You must have an income of GBP18.6K and a verified Bank Balance of GBP5K for a 6month visa. Clearly establish a reason for the visit. ie, tourism, family visit, or leisure. Get rid of the agent and do it yourself.
At least he is learning to defend himself but that can't take the place of street smarts which was your job and common sense. Maybe you should come back and take him yourself or send mum?