What do you mean by Seriously? Are you under the impression that everyone over 50 has an income of over 65,000 THB per month? That is equal to £320 a week UK, or $400+ USA. Must be a lot of private pensions to get to that amount.
Which immigration office that won't use the combination method? Can't understand why. 65k a month doesn't come to 800k a year, so don't know why, say if for instance a person has 400k in a Thai account and over 400k a year transferred into same account on a monthly basis.