Hi Negesh,
As far as i understand your LAN network missing from CityA side.
First of all we need to check if the network begins received but not selected or doesn't received at all.
So kindly provide the output of
CityA-Router#Show ip bgp summary
CityA-Router#Show ip bgp
If the network received but not selected we can go further and troubleshoot it, but if it's doesn't received you have to open a case with your Service Provider regarding that.
Please rate helpful posts.
Best Regards,
Mounir Mohamed