Well my seat belt locks under wot anyone else had this problem?

 

Why would you be worried about your belts locking while you're accelerating? Just be happy that your seat back doesn't collapse. But to answer your question, they sometimes lock up, it's a matter of giving them some slack and freeing them up from the locking mechanism. And for the record, the locking feature is what makes the belts functional, don't complain. You could try to readjust the assembly if it happens all the time. They're very sensitive to the mounting angle. If it's obviously defective and always locking up, then you might have some luck taking it to the dealer and having them replace the assembly.