Sorry, it’s kind of meaningless. Why did your friend recommend this company? Just the fact that you need to pay before you know if you will be accepted or not makes it sound like a scam to me.
It is generally always better to go through something that you know is officially approved. What kind of J work would you be doing? I gave you the officially approved list above, you can at least contact a sponsor in the field you are interested in to see if they also want to pressure you to pay them $4k...? I mean, this agency might be legit but upfront deposits and pressure for lots of money in a short time after that sounds scammy. When in this process do you actually go for the visa interview?