I think most would say that it's ok to phone or email once, but not more. If you get no response, it's because there's nothing further to say to you. If "they" had something to communicate with you, "they" would do so. Contacting them more than once is annoying and so probably not a good idea.
While you're waiting quietly for followups, you can practice your spelling and review the rules for using capital letters. That would be another way for you to be less annoying.