1k?? I had mine replaced in 2019 during building works for £500, they had to use a mole and finally connected 25mm mdpe and joined up to Thames water stop cock in pavement, that was in London as well, got teh company name from Thames water website.
They should have Building Regs Cert if they went through build regs, if not then its a 3 bed not a 4, a bargaining point if you really want the house, but you wont know if its structurally sound.
You need a flexible filler, use toupret fibrefill filler,let it cure then refill then paint.
The toupret fibrefill is quite difficult to work with (cant be sanded and does sag so may need 2 applications) but best to use on the flat service and use your other preferred filler on the cornice.
I have a salus it500bm, only use for combi, i like the internet app which is simple and easy to use, however they had real problems last nov when their cloud server kept on keeling over, but overall its worked ok.