for me it means nothing as I see the bigger picture which things definitely has changed in this provider
Maybe you have changed? You used to be lucky, now you are not... You say that the slot "must" give you something... it doesn't have to! I think you have too high expectations, maybe you used to wine, now a bad period has come and that's it.
By the way, you are talking about normal bonus buys, I have losing streaks with super bonus buys... imagine that? Buying a super bonus with $100-$200 and winning $1-$2 (x5-x10). But I am not complaining... we are talking about slots. Many times I wrote here that slots are tricky, they can give a lot, but they can take even more.
It's disappointing when results appears to be far from expectation. Funny enough it's not about how much you decides to spend, you could spend so much and win nothing or less while the next guy spend three times less of yours and get a lucky huge win.
Making complains wouldn't change a thing because at every point of your loss there are others incurring higher losses than yours, so it's either he quits from playing pragmatic slot or make use of an amount he would have no course to complain if lost while also hoping you get lucky someday's.