I think because of all these new plans fiasco, their systems might be overloaded or not functioning properly...I didn't try to add/remove any channel but I just tried to login on the site & the site loaded normally for me...I think, the slowdowns or not being able to add/remove channels are because of the new pre-paid plans or they might be revamping the app/site as Airtel has every services of them integrated into one...So, if one part is affected, others may too...