Well I have played in a few other casinos the same Pragmatic slot and the same has never happened to me, max consecutive lost buy bonused I had in really rare rare cases is 8 and never more than that, I have lost there too but I don't come writing posts about the way I have lost as they were normal type of losing session compared to what I have suffered in Stake. Again I invite anyone to hit 17 consecutive lost buy bonuses, not normal spins but buy bonuses and you will not encounter this in any other casino except Stake, always I am referring to Pragmatic Play.
And which slot did you play? 17 bonus buys on one slot or multiple slots... I have also had very bad streaks on many providers with many slots. I may have had more than 17 constructive losses (when I get less than what I spent on the purchase), but not on a single slot. Sometimes I can't hit anything for weeks, losing deposit after deposit. Slots are tricky as hell...
For example, Pragmatic didn't give me over x130 (more or less) in months... counting all the bonuses I won from normal playing & bonus buys. I also bought super bonuses more than once and they barely returned my investment or gave me some minimal profit. Nothing big and grandiose for me from Pragmatic on whatever site I play it...
Well, I don't think it's about Stake... but I understand how you feel, I too have a list of providers and casinos that I don't like. You will find another good place & maybe you will be luckier there. Good luck!