Lenovo — lenovo z2 plus not get nougat update

Address:

Patna, Bihar, 800020

I had bought my lenovo z2 plus from
yaantra on 11-10-18.It's going to be almost 2 months but thenougat update hasn't reached me, whenever I open system update it doesn't show the update.I searched on the net and it showed me to wait for 7-8 days but not it has been almost 2 months, so kindly give me a solution for it ASAP.

My mobile model is Z2132 .