Neglected cat?

[WombatStewForTea]

One of our neighbours (pretty sure I know which house but not 100%) has a gorgeous and very friendly bengal. It likes to let itself in our house through any open windows - with no encouragement needed and its a bugger to get him to leave.
I noticed about a month ago that it had a lump on it's head and it was there the next few times I saw the cat it still had it. I assumed they'd be taking it to see a vet. Anyway it let itself in again today and the lump/abscess has popped and the cat now has foul smelling pus coming out of the quite large hole in it's head.
To be honest I'm quite concerned that this cat needs to see a vet and it clearly hasn't. I'm also pretty sure it has ear mites and it regularly has lumps and bumps but I assumed it was because it was a bit of a fighter.
What, if anything, should I do? Talk to the people I think own the cat? But what good will that do if they haven't taken it to a vet already?!

[thecatneuterer]

In that situation I would speak to the people and just say he keeps coming into your house, and you'd noticed the lump/ear mites and was a bit concerned. Ask if he's been to a vet recently and, if not, I would offer help to take him (say you thought they may not have the time etc etc). If you don't come across as accusatory but make it clear you are just offering help it usually goes down better.

Your next move all depends on their response/attitude.