Service Engine Light On problems of the 2012 BMW 328

In March, 2013 service engine soon light would go on and off and engine idle would suddenly surge. Made service appointment with dealer where I purchased the car and service department diagnosed the issue as a faulty secondary air valve, fc 2a00, DC d1170-000 07-001, and secondary air valve was replaced. Parts replaced: 11-72-7-506-214 and 11-72-7-557-909. Car was purchased on 10/8/2012 and had 5,333 miles when it required repair. After the repair was done, the service engine soon light was no longer on, but the car continued to experience engine idle surges, but they were not as abrupt and significant as before the repair and a lot less frequent. However, in July, 2014 the car started to experience issues relating to the engine overheating, and the engine began to have frequent and sudden surges both while at idle and while driving. In addition, the car's a/c was no longer providing cold air, and the car's performance was erratic. When max cool was engaged, the car's engine would surge loudly until the a/c was turned off. The car became increasingly difficult to steer and drive. During the time the car was experiencing these issues, no warning light was illuminated and the on board system check indicated that there were no issues with the car. At this point the car had been driven14,000 miles (approx). Service appointment was scheduled and according to service department, the a/c system was leaking and there was very little refrigerant left, and the a/c compressor was replaced. However, the service department stated no other issues were found with the car and when the service tech test drove the car it performed without any issues and they did not observe any sudden surges with the engine.