First post on here, hello! :-)
We have a minibus, it's adapted with a ramp at the back, drivers seat turns so my husband can get in and out easily with his powerchair. It's a bit knackered, needs a lot of work to the body, but it's clearly a wheelchair accessible vehicle, not a builders van or something.
We park up on a main road, next to a lowered curb, to fetch the kids from school. We have to drive as we've moved house and the kids have had enough stress over the past 3 years without changing schools again too. Dh often gets out and goes with me, if it's nice. Quite a few times, we've had people park over the lowered curb behind us, but they've noticed the 4 various signs on the doors saying 'please leave 3 metres for access' and given enough space.
Yesterday we parked up a little early, to go to the shops. I nipped back to the minibus on my own to drop something off and noticed someone had parked right up over the lowered curb, too close to get the ramp down. There was another car's length at least empty behind them, so they had deliberately decided to park that close- they could have reversed up a bit to give us space.
Got back with the kids and the car is still there. No room to get dh back in (and he's the only driver).
We waited. All the other parents parked up nearby left. Got fed up, called the local police and they said they'd send someone out.
Just before the police arrived, a couple with a baby came strolling back- staring into the van as they walked past, then proceeded to get into this car- they weren't going to speak to us or apologise.
I have two noise levels- very quiet or very shouty. After 45 minutes standing in the heat waiting for them to come back, I was fuming. I told them we'd called the police, that they'd blocked us in. Their attitude was 'we can park where we like' and 'we made a mistake, but you won't resolve this amicably'. They then pulled out into oncoming traffic and nearly hit a car.
Is it acceptable to knowingly block in what is clearly an accessible minibus? And stand watching from a park (realised after they were the people doing that- maybe waiting for us to leave or something or wondering why we were photographing their car... I nearly went over to the park and yelled out the reg number- dh wouldn't let me
). And then get shirty about the people you've blocked in being upset and pointing out 'mistakes' have consequences?
Policeman suggested we buy cones to put behind the van! Shouldn't have to get that far- what happened to common sense? We don't have an adapted minibus for fun- I doubt they'd swap. 
I'm a little bit stressed about other stuff and this has kind of tipped me over the edge. 