Short term study of Chinese for 4 or 5 months

Hi.

I am a Canadian passport holder and going to apply for Chinese X to study Chinese language at a private language institute in China.

I want to stay in china for about 4 or 5 months. I had got 60 days L in Vancouver 3 years ago and studied Chinese language at the language institute.

I don't think the institute can issue JW202 or JW201 form for short-term study, because it is privately owned language institute.

1.What is the best way to get a 120 days or 150 days single entry X for me? and what are necessary documentations?

2.What does official seal mean?

The owner is willing to supply me whatever I need for application

Thank you.