Airtel — outgoing validity expired so asking me to do every month 35 recharge

Address:

Hyderabad, Andhra Pradesh, 500007

I am using airtel from a long time
i did not put any other sim except airtel
i dont have any other sim
more over i recharge frequently
my balance is 1500 n above

Every 28 days we must recharge for 35 for validity,

that's not correct,
it is my wish that i recharge,
with plans intresting to me,
if you can help in some way then please tell,
i am using airtel since longtime,
want to continue the same,

every month paying 35 extra, then i would prefer the next best network