Renewing your passport can be a bit of a chore, particularly for those of us who live a long way from Bangkok. I have very recently renewed mine with the help of Darren McGarry of Key Visa, based in Pattaya. From the moment of initial contact to my new passport being delivered to my home, Key Visa were friendly and extremely efficient.
You simply download the appropriate forms from their website, fill them in, send them with your old passport then sit back and let Key Visa take over. The whole process took just over three weeks.
Their fee of 5,100 bht was more than worth it and I can wholeheartedly recommend the use of their services.