@Leo ******
The UK and Thai government are both working towards visa free travel between both countries, so is the EU. Syrian applications, as of 2 days ago, are all suspended. My wife had been imprisoned and deported by Malaysia, and we got a visa no issue. Possibly its your circumstances or your invite letter that screwed things up, not her. We used an agent, but that was good value by the time you factored in travel to Bangkok, a hotel, taxi costs etc. The agent showed me some of the covering letters from some of his English clients, and I found them to be borderline illiterate.