salaam @ khfhasan,
I want to tell you this that even if you get the transmission fixed you will still get the same problem again , why you ask , because this a generic problem in the steermatic and vario transmission of a Honda City.
According to Honda Engineering department , a pair of variable-diameter pulleys, each shaped like a pair of opposing cones, with a metal belt or chain running between them. so it is this metal belt which gets lose and slips, due to which the RPM of the engine drops followed by a jerk and a tapping sound on the firewall .
After getting my transmission changed i do not face this problem , because i have been following the tip given to me by the Honda ,which is always put your gear in (N) neutral or (P) park when the car is at a stand still to ensure the reliably of the transmission.
All i can think of is to get your car checked by Honda again and specify them about this issue , if so i would recommend Honda SITE Karachi , if you live in Karachi.
i am again telling you my friend your problem could be something else also , but the symptoms that you told me and we both also agreed on them , then it is most likely the transmission belt , but again do take advise from professionals
bye.