I did my extension of stay for retirement a few days ago, this is the 14th time I have renew it, never used an Agent, I always use the combination method, 402,000 Baht in the bank and about 42,000 Baht income pension each month and did it at Jomtien since 2012, I get an statement from the bank for the income each month, and an letter for that Statement and an letter for the money in the bank 402,000 Baht , so must have two letters, it takes about 30 minute at the bank, must have all the copy of the Passport, and Bank books, contact for the rent of the house I live in , 1900 Baht for the cost of the extension of stay, it takes no more than 20 minutes at the Immigration at Jomtien , all finish, pick up Passport the next day and Bob your uncle all over red rover for another year, very easy, if you have things correct you will never have any problem, never had a problem at Jomtien or Bangkok, any one can ask me and I will tell them how, no need to pay agent.