disconnection from server,black screen with sound but no picture,3,4 seconds game delay

for a start am new to this game,playing like 4 months,and i can say that i know how to play and each game i am imrove my skills,now,problem is a lot off disconnections from server on start game,or a black screen with sound and no pic,my pc and my internet conn isnt problem coz i check it, t-com,my provider check it,coz of that i gather a lot leaver buster bans and its not fair,it reconnect me in 5th or 8th min of the game every time,and i mean really every time,thats more often when i play against jhin morgana mundo twisted fate and sometimes jax,when i play against jhin every time i att on screen just show atempting to reconnect for 3 4 sec,and next i know i am in base dead,when i play normal its ok in 99% of the case,but when i play ranked its terrible, i am five lvls behind my teammades and its often lose game,i love this game,i am trying to do my best and these problems must be solved,its not fair that some players got advantage and me and my team got score like we r some dumb noobs,hope you solve these problems who put me on leaver buster ban and put me from bronze 3 to bronce 4,thank you