The amount of available bandwidth you have (In this case, 1200/300 down/up) has almost nothing (let me repeat: almost nothing to do with your PING time (latency).
It is almost entirely dependant on the hardware involved, the physical line (medium) being used, and, most importantly, the distance, not always physical but electrical, between you and the server you are connecting to.
There is very little you can do to improve your PING, especially when it is already falling into a normal range. 50ms is absolutely excellent for online play, you should consider yourself lucky.