Airtel — Number allocated to other within 7 days of disconnection

My phone got discontinued on 05.04.2015 due to non usage for 90 days & also due to low balance. On 05.04.215, I got SMS that “Aapne 90 din se aopne airtel mobile [protected] ka istamaal nahin kiya hai. Sevayein jaari rakhne ke liye dinaak 21.04.2015 se pehle apne mobile ka istamaal karein” On 13th & 14th April 2015 we tried to recharge but it was not getting thru. We visited the airtel offce in Jodhpur on 15th April to re-activate the number but shocked to know that the no. has been allocated to someone else. This is not fair. You send different message and does something different. How come my no. was allotted to someone else within a week’s time. Airtel should not allocate the number to others for atleast sometime and give consumers an option to re-activate it.