self employed NI contributions not showing on account

My wife is self-employed and earned between £6700 and £12500 for the last 2 years. It's my understanding, she didn't need to pay voluntary class 2 NI for those years - they should be automatically credited. However, for those years her record is showing as 'year not full'. This is very frustrating, as we are desperately trying to avoid gaps at this stage. Also, the cost of filling these gaps is quoted as around £800. I thought it was cheaper if you are self-employed? Thanks for any help with this situation,

Hi Giles Hindle,
To assist you better with your inquiry, your wife should reach out to the National Insurance department on 0300 200 3500.
National Insurance: general enquiries
Our advisors will be ready to help her. 
The tax years displayed on her online records will only reflect the Class 3 rates of National Insurance.
If needed, an advisor can provide the Class 2 rates.
Thank you.