Right.
Thanks for clarifying all this.
In your position I would write and/or email them stating the problem and giving them a week to sort it out, and that if this does not happen you will be taking the legal route.
This is the normal way of doing this sort of thing.
They cannot simply say they are not refusing, because they are continuously avoiding doing anything on it. Promises mean nothing especially if they are not kept.
If they write anything to you "Without prejudice", tell them that if they are not prepared to communicate properly with you you will ignore it.
I have had this happen before, it is just another way of trying to persuade you to basically allow them to muck you around still further. They need to know that all communications will be put into the dossier that will be brought to court should it be necessary.
It is obvious they cannot fix the problem easily and cheaply so they are fobbing you off to enable them to work on other more lucrative stuff.
Their problem, not yours.
I really do feel for you. No one likes to have to behave in this manner cos it seems kind of unreasonable. But it isn't they are being totally unreasonable and hopefully a good legal kick up the butt might get them moving.
Many young people and not so young, would say "See if they have a Facebook page and p!ss all over them on that" but you said that their profile as regards repairs was already bad, so it may not make any difference.
I don't know if I could be bothered to do that.
Best of luck with it all
Stan