Apple India — ios 11 slowed down my phone

Address: 695582

Website: www.apple.com

I updated my iphone 6 to ios 11 recently. From then, my phone is getting stuck, is very very slow, and is having lot of issues. My phone was in very good condition and is not even 2years old. I don't have any unnecessary applications and have enough memory.
I feel like apple is trying to slow down all the older versions of iphone with ios updates so that people will keep buying new phones.
I have read many similar complaints.
If this is not resolved, we will be forced to go to consumer court