Try to refresh ur account. If still u r unable to watch channels part of FTA Complimentary Bundle go to Airtel App, select the DTH account , press manage tv channels tab, go to airtel service section and there u will find FTA bundle pack listed under "Airtel" category/option. If u can't find it there then again go to main menu of dth account, select my account option, then click manage tv channels tab , go to airtel services and press "airtel" category where FTA bundle pack would b listed.
Also u can add this pack thru SMS code