How can i increase the speed of download?

Hello,i am subramani from tamilnadu.i am using nokia 2700 classic mobile.i am using aircel mobile with activated gprs,pocket internet.I Have a problem.it is follows.the speed of internet decreases when download contents such mp3 songs,videos.The speed of internet decreases highly than browsing.How can i increase the speed of internet.I have restored my mobile many times,i cleared cookies,history often.If anybody have UNIQUE idea to solve this problem,kindly reply.