BS LEAVER BUSTERS

So this has been going on for a while now and ive been messaging the riot support through email but it doesn't seem to work so hopefully you guys can help me but sometimes when i get into a game my frames drop to 00 but it isnt the computer because when i exit out it works just fine but then after a while it freezes my computer and im forced to restart and leave the game i always come back but then i get a leaver of something i have no control of i clean my pc its fast I just dont understand why i have to now wait 20 min to play a god damn game man it has happened numerous of times and the support team doesnt do anything about it please help.