Can I extend VISA after my study period?

According to Thai immigration bureau rules, students need to cancel their student visa once they have completed their studies at that particular school or university. So if you get a student visa under Siam University name then at most we can only let you clear all the projects, exams of Siam University. if the semester end on 9th January, you can get extension till the end of January only (provided that your visa does not expire before). Siam University cannot let you extend till February or later as the semester completed and also you have to complete all work before semester finished. You can see the academic semester study periods as below.

Semester 1:  14 August - 15 December 

Semester 2: 10 January - 15 May

Summer (3): 7 June - 15 August

If you stay more without cancelling VISA, student may be fined THB 20,000 or blacklisted. They have been a recent case a student in which Siam University had received a warning from immigration bureau. 

However, student can apply for a student visa under separate category or with provided proofs which the student has to contact immigration office directly, and provide necessary documents.