Trying to get national insurance number

Hi there.
My name is Jordi and my wife's name is Jezabel
We are from Spain
She is living in UK since 2014 and my self since 2013.
Since my second week, I am contracted and paying tax.
Sine 3 years ago, whe are trying get her NIN and is being impossible.
4 different jobcentre we visited, 1000 different calls, always same answer,
"here is not the right place".
Never they gave us a reason for reject us, just a new phone to call or a new appointment.
We are desperate and we are thinking on get a solicitor but, this cost lot of money and we are not
sure about the result.
My wife has lost lot of welfare since she is in UK.
She is a disable person, here or anywhere, with a rights

Know somebody what we can do?
Had somebody a similar problem?
Can somebody give us a hand?

Any Spaniard speaker?.

Thanks a lot for your time and support.