I have a single entry 90day o visa i would like to stay on longer , if i was to fly to cambodia for a few days can i still get 30days on my return? Just not sure if because i've had 90days i have to leave the country for a certain period of time before i can return . Thanks

Air arrival still gets 30 days. You do not have to leave country for any period of time. You can also obtain a tourist visa (free until June 4) at a nearby Consulate and return with that for 60 days which can be extended 30 more - and you can do that by land if you like.

You can extend a non immigrant O for 30 days at your local immigration department, cost 1,900 Baht.

You can leave the country and return straight away and get the visa exempt allowance.

No you can not. A non immigrant visa is not extend able without reason, such are wife, retirement, education or such. The most you would get is 7 days.

Thanks guys appreciate your response

No you can not. A non immigrant visa is not extend able without reason, such are wife, retirement, education or such. The most you would get is 7 days.

Yep. 7 Days if lucky. Then you need a flight ticket leaving Thailand within that time.