That is something you might want to bring to the attention of Player Support. They may or may not be willing to take another look into the case for you. However, be aware that if they do, they still may not share their exact findings with you. We don't know all the details of how they verify whether it is the same player during a match, or whether another player has gotten hold of the account, but we do know that it involves fairly unique data to each player. Riot Tantram talked about it in a thread once a while back, about how even the number and pattern of mouse and keyboard clicks that a player uses can be quantified as a sort of biometric data. It's not the sort of thing that you pick up necessarily by watching a replay of a match, but it is definitely the sort of thing that the servers track, and that anyone watching a live stream will notice.
To give you a simple example of it, I always run my game in locked-screen, player attack move click is bound to mouse button one (MB1), and player move is bound to mouse button two (MB2). As the Support, unless I am trying to help my adc farm under turret, or trade, I will almost exclusively be using MB2. And I have a standard pattern of usually 3 clicks of MB2, followed by 1 click of MB1, when I am walking around in the lane. These aren't necessarily "good" or "bad" things, they are simply part of the pattern that I, as a player, demonstrate. And every player has one. Things like this can send up a red flag on potential account compromise just as easily as a log in from across the globe. And yes, these things can have small changes, or evolve over time, but generally they are not going to flip-flop or have large changes over the span of a few maps. It simply doesn't work that way.
So, if you choose to contact Support again, you can ask them to please look at your case once more, as you now suspect that there might have been an account compromise responsible for this. Try to be polite, and patient, and above all else, try to not be demanding with them. You can give them certain matches that you do not feel were your own, and you can even tell them about some of the things that have been discussed here on the forums. But please remember, you are asking them for help, and getting angry with them, or raging at them and telling them that their treatment is "not fair!" or that what they are doing is "not right!" or anything along those lines isn't going to help your cause. And I'm not saying that you have done this, but many players do, without realizing how much it hurts their chances of having a peaceful, positive resolution.
