Collecting 3 weeks of historical tweets related to a specific hashtag



I would like to collect historical tweets to do data analysis for academic research. I submitted my application to Enterprise data:, to ask for a possible quote and I still have not heard back from them after one week. I wish to know if there is any other way to contact someone that could give me this information. Also, are there other solution I could use to collect the tweets I need, even if is not free.

I wish to collect tweet data from an event that happened already more than 50 days ago.

Your help is much appreciated.