Can I extend my SETV twice in Thailand and then return for another 90 days?

as

@J*

, said that 7 day stamp after a 30 day extension is NOT guaranteed.

Many immigration offices want to see proof that you're leaving thailand within a week before they'll sell you the "application for extension denied" 7 day stamp.

What is the country from which you have your passport issued?

The first two 60 + 30 are standard. Extending the 7 days is not guaranteed because it is not a real extension but similar to a rejection of an extension where you are told you have 7 days to leave. If granted it cost 1900 Baht - same as the 30 day Extension. Thai Immigration does not like it if you show that you planned to use the 7 days versus it was an accident of scheduling. After the first 60+30 period depending on what is your home country - it would be better if you went out of Thailand to a neighbor country and reentered to get a 30 day Exempt Entry - which can be extended by another 30 days. Then go to another country to get abother 60 day tourist visa. All this can be done if you do not have a track record of many recent previous entries

You might get an additional 7 days, I would just do a border run and get 30 days