When it comes to speaking Mandarin Chinese, why the hell does everyone say the phrase "xiexie" so weird?

It’s pronounced "shyeh-shyeh", not "shay-shay". My patience is running out for this mistake. I know not everyone knows this, but professionals on television? Really? They couldn’t even learn how to say "thank you" properly before they went on their show? Sorry. This just really annoys the hell out of me… …