Buying at BST is like buying used car. If you know nothing about cars and want to buy it based only on price, make or color you will end up buying piece of shit which will cause you nothing but trouble. If you, however, know your shit you will end up getting good deal, a car which will benefit you long term.
OP, create a private list of sellers who services didn't do any good to your sites and simply don't do a business with them again.
For those who believe BST is all shit - repeated sales from some providers make me think they sell stuff which work for some people.
This fucking shit right here. I have purchased the same package MULTIPLE TIMES from sellers who had good shit. I don't expect rankings to stay solid forever since links do drop off. But I do space packages out, check backlinks with SEO Spyglass and see what worked and what didn't. I got screwed out of a couple hundred bucks but its a learning process. Chalk it up and move on.