If you are certain that the update has caused this problem, it has been reported here that downgrading is possible, although a bit tricky:
However, the reason behind must be a bit more complex than just the 1.6 update, since very few of us who have updated have experienced the same. I’m a bit worried over dsa83’s report on support/repair handling - it might well be that the techs couldn’t find any issues when testinmg but if so they ought to have suggested other explanations. Could the operator/network somehow be the culprit?