You have not been scammed. Satellite internet is very different from cable and other types of terrestial internet. You may need some help to learn how to manage and use it within its limits. I'm tagging some Hughesnet mods and others as well. Someone will be along as soon as possible to help.
The issue of Netflix being "slow and touchy" may have to do with the Video Data Saver. The VDS is designed to throttle the service while streaming in order to save data. It's designed to throttle the speed to such that is amenable to streaming in SD, so if Netflix is not set to be able to stream in SD or lower it can cause buffering issues if the VDS is on. You can try lowering the definition of Netflix to SD or lower (or set it to auto) or turn off (or pause) the Video Data Saver.
Keep in mind, though, that streaming can use a LOT of data, and if you've been doing a good deal of streaming with Netflix this is probably why your monthly data allotment is currently exhausted. Once your data is exhausted it will not be refilled until your new monthly data cycle starts or you purchase data Tokens.
Edit: The Video Data Saver may also be causing the problems with streaming with Sling TV. Again, though, streaming will use a lot of data, especially in HD. So, if you turn the Video Data Saver off (or pause it) in order to stream something in HD, you're data will be used up to the tune of 3GB or more per hour.
Additionally, if you are currently throttled because you are out of data, your speed may not be high enough for watching videos are doing other data intensive things, though it should still be high enough for general browsing.
Welcome and thanks for posting. The advice Gabe posted above is definitely good to keep in mind, here are additional tips on managing your data to make it last throughout the month.
I ran remote diagnostics on your site just in case anything was amiss, and everything is working properly. I do see you have a DirecTV device connected, these can use a LOT of data. Yours used around 4.5 GB since last Friday. I suggest keeping that offline (disconnect from the modem) until you need it online, otherwise it will be consuming your data in the background without your knowledge.