Try "огромное спасибо" for instances of extreme thanks. When someone treats you to a remarkable favor, you could use this phrase to say “"thanks a ton" or "a giant thank you”. This will express a form of gratitude even greater than that expressed with "Большое спасибо".
Switch to "Благодарю вас" for formal situations. If you need to express gratitude while showing a greater degree of respect than usual, this is one of the simplest phrases you can use to do so.
Pronounce "Благодарю вас" as: bla-go-dar-ju vas
The English equivalent of this phrase would be something along the lines of, "I am much obliged to you."This phrase would be appropriate to use with business colleagues, elders, or strangers.
Soften formal thanks with "Благодарю от всей души." Try using this phrase to express extreme, heartfelt thanks in a polite or formal manner. Essentially, you're telling the other person, "thank you from the bottom of my heart" or "thank you with all my heart."
Pronounce "Благодарю от всей души" as: bla-go-dar-ju ot vsey du-shi