The Chess.com server controls the chess clocks.
https://support.chess.com/customer/en/portal/articles/1444849-why-did-the-clock-times-suddenly-change-the-clocks-seem-broken-
It is also possible you had temporary disconnects.
https://support.chess.com/customer/en/portal/articles/1444918-my-internet-connection-is-fine---why-am-i-getting-disconnects-
https://www.chess.com/blog/News/how-to-adjust-your-live-chess-connection
[public accusations not allowed -- MOD] on chess . com cheats by stopping his time when losing, and your time ticks away. Cheaters should be removed