Only in extremely rare circumstances have I ever used an agent. At the end of the day they are there to make money and make money they will. Most stuff you can do yourself.
Ive had some snotty IO's over the years but nothing quite like your experience, the normal questions are how long you plan to stay, what do you do for a living and occasionaly do I have onward travel. I always reply I intend to stay less than the 30 days given on the exempt. If there is ever going to be an airport to get a grilling it is Bangkok so best to avoid there if your travel history is pushing its luck a bit.
They are generally the cheapest but you do have to tread carefully as they use lots of scammy tactics that can bump up the costs considerably, as for customer service it's one of the worst. I still use agoda from time to time but wouldn't use for things like international flights as if something goes wrong you will find the airline won't rectify anything as its all booked under agodas authorisation and agoda will do nothing to help. I've had to make many bank charge backs due to situations like this or had to pay the airline extortionate fees to over ride agodas admin on the booking.
As someone who was in a similar position a few years back a lot of the comments here are just rubbish, yes the NHS is overloaded but if you have a serious health concern you will stil get treated fairly quickly. It really boils down to what the health condition is and the severity. but yes if urgent you will get seen quickly. Id also say little as possible about living elsewhere just act like it didnt happen and if you somehow get pulled up on it then you make some excuses.
Some of his points are not wrong but you have to roll with the punches here and learn to make it work for you. On the flip side most western countries are awful to live in now certainly the UK for instance. Thailand certainly has its faults and drawbacks but there are far worse places to live.
qatar are absolute cunts mate, still haggling me for a refund after covid, first they insisted I can only have a replacement flight, then it was they would only pay the tax as a refund. only recently they are prepared to refund me the money i paid for a flight they cancelled. Sorry going slightly off topic but yes their cunts.