Advice on Garage Party wall

[Hyperion2020]

Hi DIYers

Next to our new home (three-bed semi) is a standalone double garage, and one garage is ours, the other's the neighbours. It's flat-roofed, external walls single leaf brick, and between the two garages is a blockwork wall. Our surveyor noticed cracks in the mortar of this blockwork wall, and noted that when you nudge some of the blocks, they move. Since moving in, we've had a look - it's just two of the blocks at the top of the wall that move when you give them a gentle push, but there are cracks in the mortar down 5 courses from the ceiling in places.

So - advice, please! How would you approach this, without costing the earth?

I'm aware of the Party Wall Act, but tbh I don't want to go to the time/expense, nor do I want to put the neighbours' noses out of joint by going 'legal' on them. Plus, I believe you have to disclose any Party Wall Agreements to prospective buyers and I wouldn't want this to put them off...?
I'm also aware we could just go ahead, get a builder in (post-lockdown!) to re-point the wall from our side, and save on the paperwork?
Or, be a bit cheeky and drill/screw in wooden batons floor to ceiling which would stabilise it, and fit some shelving, pretend it's all fine?

Any advice much appreciated, cheers!

 

[^woody^]

Er, it's a repair, you can just do it.

Obviously you need to tell them and may need access to clean up. And if you want to share costs tell them the price and half it.