It is not really a mystery: "that would be so helpful". What don't you understand?
Is there another way to say the last part I've underlined?
If you could please look into cancelling our room for us that'd be so helpful.
No, I mean another way to express that sentence?
I would be so grateful...
you'd be doing me a big favor...
Any other ways of expressing that idea?
Could you help me by listing a few?