Just for information for community: went today to Patong immigration office to extend visa exempt for 30 days (german passport). Went smooth, you only need copy passport, copy stamp, one photo, TM7 sheet (you'll find it there), pay 1900thb, wait 30 minutes. In Phuket Town immigration they told me, they need some residency forms but in Patong nobody was asking for this. If you have further questions please ask, just wanted to share my experience maybe it's interesting for someone. 👍🏻🙂