Jam Loey Rak (1988)

Soraya was sent to see a guy because Sansanee, her cousin, told Soraya to go in her place. The guy's name is Harit. His brother killed himself after breaking up with Sansanee so Harit wants to take revenge. He kidnaps Soraya thinking she was Sansanee. He takes her to this house where no one is around and basically tortures her, no matter how many times Soraya tries to tell him she's not Sansanee. She ends up accepting all the punishment doled out by Harit due to her wanting to repay her debt of gratitude to Sansanee because she once saved her life from drowning when they were young.