tl;dr - just because someone says they're meant to do something, doesn't mean they've done it.
I had a similar response from Surrey CC when I had a banjoed mountain bike wheel from a hidden pothole during heavy rain - it wasn't a cheap bike (thank you bike to work scheme!) and the new wheel was c. £90.
As I was skint (hence riding a bike as couldn't afford a car for the 24 mile round trip) I put in a claim, but got short shrift. They said they inspect it every 6 months/180 days (can't remember exactly which now), so they weren't liable.
It wasn't so much the fact they dismissed it, that annoyed me, it was the 'be quiet pleb' way they did it - there are polite ways to tell people to p*** off.
Unfortunately, I worked at a neighbouring council so am more than used to bureaucracy and the byzantine workings of local government, so didn't let it go.
I politely emailed asking for the schedule of maintenance inspections for the last year, and after the auto-reply confirming they'd got it, didn't hear anything.
I gave it a month (21 working days to be precise) before I forwarded my request back to them saying I was giving them 48 hours to respond to my request for information or I was reporting them to the ICO for breach of FOIA. Cue a hasty reply, saying that as I hadn't said "FOI" in the request, they were now going to treat it as an FOI and start the 20 working day clock, and they'd cc'd the FOI officer to "save me having to send it to them again".
Now, I'd also worked at the Cabinet Office when FOIA was born, so I replied straight away (keeping the officer cc'd) saying nowhere in the act does it say you need to say it's an FOI - it's any written request for information, to anyone who works in the authority. Weirdly, the FOI officer tried to argue this, so I sent them a link to the legislation,whilst secretly loathing the person they'd turned me into.
A couple of hours later, I got the schedule, and 'several' pages of explanatory text about the things they measure, what constitutes a defect etc.
Now, being in full on bureaucrat mode (I'm hating myself again, writing this...) I of course read this with interest and was delighted to write them a reply pointing out that their inspection of my bit of road had last happened six months and four days/184 days (still can't remember the deadline, but remember exactly how far over it they were!) before my encounter.
This led to some more back and forth about the maths involved in working out how much time there was between two dates (I was truly committed now, so wasn't letting it go) until they finally went quiet, and a couple of days later a cheque arrived in the post.
As a long-serving/suffering public sector worker, I don't like to be on the other end of this kind of childishness, but equally, I like to think I wouldn't have created the situation in the first place.
The people dealing with the claims are essentially trying to preserve the council's insurance bill - which is fine. But I think they could be less officious about it, and might do better applying pressure to their colleagues over in the highways team to at least stick to their schedules, even if they can't afford to do the full resurfacing most of the roads need.