how do i request a P6 form

my employer is using basic rate for my tax code and has told me i should request a P6 from the tax office, but I've tried 5 times and was waiting over a hour and twice just getting cut off because there was no one to answer the phone. i have created an account and its says my tax code is 1257L.

Hi snowy osborne,
We apologise if you are having difficulty getting through to the helpline. 
If the code on the online account doesn't match the code the employer is using you will need to keep trying to get through to update. 
Income Tax: general enquiries
Thank you.