Precast Concrete Cornish bungalow

Hi, I’m trying to sell, unsuccessfully, my mums Cornish type 2 bungalow my dad built in 1961.

house was rendered soon after construction. No cracks inside or out lovely and warm property. I understand the problem lies with the vertical pillars the large slabs are slid in to? And as the roof sits on these pillars a whole new load bearing outer skin is required?

costs seem to be in the region of £60k. Is there any alternative like bricking up on the inside?

photo is of same property prior to rendering

thanks