HI,
So a number of different things:
1. You do not HAVE to specify the hreflang in your sitemap if your are doing it correctly in your page code. If you want to anyway then see this page for details on how to do it.
2. In your pages you should NOT have 2 hreflang meta tags. Each page should only have one tag. In the thai page a tag pointing to the english version and in the english page a tag pointing to the thai version. Right now you have 2 hreflang tags on each page.
3. For the %20, this is from having spaces in your file names. You should ideally not have these. If you change the page urls you should 301 redirect the old page with the %20 to the new page. See here for details on how to do that.
Generally I would suggest that you make sure your english urls are in your sitemap (I did not see any) and then use Google webmaster tools to make sure all your pages in both thai and english are being indexed properly. If your pages are being indexed ok then I would try to make sure that there is no thai content on the english pages, this could be confusing to google especially since the two languages are so different (completely different characters).
Hope that helps!
