@Milos ****
report back on what happens,
IF all they'll sell you is a 90 day single entry Non-O you could take that, come in, get stamped in for 90 days, then apply for a 60 day extension based on visiting thai family (it doesn't require proof of funds). That would give you 5 months in country before you'd have to go to the thai consulate in Savannakhet and get the year-long, multi-entry Non-O.