To much of a coincidence it going wrong just after you fill up I think. It sounds more like a bad filling station rather than a general fuel problem. I always try to get the best grade of fuel available but sometimes that is only 95RON E5 which is pretty crap; the performance of the bike suffers but I don't remember any knocking. The bike should take E10 but I'm not going to try it.
As BabyD says, temperature is not a problem. I've had mine up to 107C in sweltering conditions in a German traffic jam (they don't like you filtering) and and up to 81C down a Czech autoroute without any problems. It gets damn hot in central Europe