I'm profoundly indebted to you.

John: 'Thanks to your help, I managed to finish the report on time.'<br>

Alice: 'I'm profoundly indebted to you; I wouldn't have done it without your assistance.'

John: 'I'm profoundly indebted to you; your kindness means the world to me.'

Alice: 'Your support during this difficult time has been invaluable.'<br>