National Insurance deadline... If you were self employed is it still £824 owing to top up each year?

I had a bit of a shock looking at my partner's NI record as I've been nagging him about the loing deadline for his state pension (he only has 10 years till retirement). He only has 9 full years built up. 😫 At least it's in time and I'm going to have to help him with the money. But I would dearly love if the costs can be reduced. They say he can back pay a maximum of 8 years at £824 each, totalling £6593.60.

He was self employed the whole time. Is it too late to get them at the class 2 rate? Is there any point even trying? It's from 2006-2014. I'm wondering if there was a cut of point where if you haven't paid them within that time frame, the only way now to get the full year is to pay the full £824. But it looks like with his self employed earnings he would normally only owe £179 per year.

I'm going to help him pay it but on the condition he gets his act together and pays it for the next ten years when it will only be £180!! I just wanted to know if there's any hope of reducing the bill?!

EDITED TO ADD... My question is not about why he has gaps. I need to know, is there a cut off point after which HMRC will only let you backfill at £824 a year, even though at the time it was class 2 voluntary contributions that would have been £180 per year? Has he missed the boat on getting it cheaply since it's 10 years ago, or should the old price still apply? Is there any hope that the repayment could be cheaper than I anticipate?