The process to become allowed to be called a TD is pretty hard and selective, so there's no need for constant check afterwards.
Every complaints we get is dealt with the TD and 99 % the time, the TD did nothing wrong but the member was just not prepared well enough, then for 0.9 % the TD will immediately sort it out, those usually concern delay in response or simple errors, the last 0.1% is when things need to be worked out a bit more because the situation is unclear, but we had very few TD removal along those years because the selecting process is pretty good
In the end we just recommend them because we know they can be trusted and they will work with us to solve problems, that's the extend of our implication in this business, nothing more