We get around 5.25% in Australia without really shopping. But it also needs to be mentioned , the convenience of using an agent. Yes it's not too difficult to do yourself but moving to a new country has many challenges, why not make it easier the first year or two.
Which is not such a bad thing. 800,000 in a Thai bank earning little to no interest meanwhile back in your own country even in a simple terms deposit you will make enough to cover your agent fees and have some money left over.
No you haven't aired it in the public arena. Your word against theirs. The threat of a really bad review has worked for me many times. I have even drafted a copy for them to read on occasion, to let them know I am serious.