Your red bus line is HUGE! Thousands of Cims will see this as their best option for their route if their departure and destination point are near bus stops. Many, many different routes will be served by this line, which means cims will cram onto the buses and fill them up. At the stop in question, I bet almost every bus turns up and is already at 30/30 capacity. The metro stop will only make things worse, as cims will get off the metro and then try and get the red bus.
First thing you could do is create an new bus route that replicates the red bus line but goes in the opposite direction. That way a cim wont occupy a bus for 90% of its loop if he wants to go two stops in the other direction. You should also do that with your metro loop.
Second tho, your public transport should be hierarchical. Metros should be for regional travel, with buses for local travel (moving people to and from metro stations from a small area). Your problem is that your bus system is trying to do what should be done with a metro. Buses don't have the same capacity as metro trains and will get overloaded.
