I got a problem with hostable's super cheap hosting

I bought hostable's $0.99 three years cheap hosting and yesterday I got a problem,actually a 500 internal server error.I searched it in Google and find many people have that problem.Some said that it's caused by site directory permission.I changed the permission to 775 or 777,but's it's still 500 error or even worse,before that error appears sometimes,but now it's all that.I submited a ticket to hostable.
They reply me like this

Hello ###,

Thank you for contacting Hostable Support. I'm very sorry for the inconvenience and we definitely appreciate notification of poor server behavior, our admins will be notified and look into the server you are on. If you have additional questions please contact us again.

Sincerely,

James
Customer Support
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Obviously they don't know what happended,I change the permission back and uninstall some plugins,the error goes away.I think it's caused by the wordpress plugin Google Sitemap Generator.I post 20 posts everyday and the plugin has to create zip files from time to time.SO it caused permission problems.I deleted it and now it works fine .

Maybe they've oversell their hostings.At that price,you can't get good hostings.

Though you have sorted out the problem, it still remains. And if you make any alteration it will occur again. So it is best to report the problem (with exact details) to support team, so that in future this problem never take place again.

If the problem still continues you can use some reliable hosting service providers.