You are doing me a great service, and I'm very grateful to you.

你正在帮我一个大忙，我非常感谢你。

《柯林斯英汉双解大词典》

You have done me a great service, and I'm very grateful to you.

你帮了我一个大忙，我非常感谢你。

youdao

I'm very grateful to you for your kindness.

你的好意，我十分领情。

《新英汉大辞典》

William Hague, I'm grateful to you.

BBC: William Hague

And I've heard that you have prepared a delicious and, hopefully, healthy snack for our children. (Laughter.) But we're grateful for you, and I'm looking forward to meeting you all.

WHITEHOUSE: The White House

And, again, I'm just grateful to all of you.

WHITEHOUSE: Remarks by The First Lady at USAID Agency visit