Airtel — 100 rs recharge went in vain for 3 numbers

Company have changed their process of minimum recharge from 49 to 99 without any communication to the users. I have done recharge on my 3 of numbers of rs 100 each. But the validity didn't extended. When I called them they say that we need to do a validity pack of 99 to extend the validity. I'm not sure why do we specifically need to do that recharge rather we should be able to increase the validity by doing any recharge higher then then minimum recharge value. When I spoke to customer care she confirmed that no communication have been shared by Airtel regarding the same. Users need to goto Airtel app to check that. In India not all users are aware to use their app. Basically airtel is not transperent and are cheating users