Well there's always faceit or just buying a new account.
Take into account that it's faster to rank up when you perform against higher ranks, this way I got to GE (this and not playing often, like I played 1-2 times per 1-2 weeks, you need several accounts to make such "pauses" from each of them).
I was like MG2 and I used that cool ingame feature called "Looking to play". The vast majority of invites you get are from even lower ranks but sometimes you get invited by higher ranks, e.g. I got invited by LE/LEM/SMFC lobbys and if you get many kills there the game will count it higher than when you do that against the same rank as you are, and surely when you win against higher ranks you get upranked noticeably faster.
So to uprank faster:
1) Play rarely, like 1-2 times per 1-2 weeks from the same account.
2) Play against higher ranks, for that mix up with higher ranked lobbies.