No service half of the time

So I ordered a rain sim unlimited all day data customer service was great and I got my SIM that part was all good. Now that I am connected an sorely disappointed the connection show full signal strength but it is so slow and forever freezing sometimes it says no internet this is so stressful because I now have to supplement. I expected better was so happy that finally a service that will give internet connection without robbing me but now I feel ******.