On the internet there are many references to "station stop". Language changes, and while I've been out of Britain, change hasn't stopped. On a train there I hate being referred to as a "customer" rather than a passenger, but that's change in language usage, too.

Judging from the reference to "Manchester Piccadilly" I would guess battybilly is talking about UK English. I was talking about the northeastern US -- where we also hear "customer" for "passenger" these days, which irritated me at first. Do they perhaps think that "passenger" won't be understood by everyone?

And "station stop" seems to be restricted to railroad English, and maybe even to announcements. A fellow passenger/customer would never say "You need to get off at the next station stop." I'm not even sure the conductor/guard would say that if speaking one-to-one.
And I'm not sure if the recorded announcements here say "station stop". I was thinking of my commuter train, which didn't have recorded announcements as of the last time I rode it, two years ago.
Seems this afternoon (UK time), you're not sure of much at all.
What's going on?
Only 4 Shredded Wheats this morning?
When you telephone a business or a physician's office you almost always hear a recorded announcement that includes "Please listen carefully to the following options as our menu has changed." I would have preferred because+ rather than +as, but I think that the same recording is probably used nationwide.
We hear "customer" on Chicago's mass transit system, too. I've wondered why "rider" or "passenger" wouldn't be a better term, but I'm too finicky. I objected when a waiter at Marshall Field's, the venerable Chicago Department store, presented me with a "guest check" after I had eaten lunch in the store's Walnut Room. I thought that a "guest" should not have been required to pay for a meal.

Being called a “customer” (someome who buys) has, I believe, a lot to do with the “market economy”, in which more and more is being turned into a commodity (and is thus for sale) by those who wish that state of affairs to prevail. Monetary gain, rather than being incidental, becomes the essential goal. A massive, ongoing revolution is taking place, one in which other people are seen, arguably, first and foremost as opportunities for profit. Many books and studies can be-and have been-written about all this.
In 1994, when I was teaching English, the management of the institution I was with (a British one, with a global prescence) wished us to begin see our students as “customers”, but I felt this was inappropriate. Seeing a person as another human being, one taking on the role of student, one with particular needs, and doing one's very best to fulfil those needs, seemed good enough. A little time later (no connection!), I received a bill from a hospital in England on which my “customer reference number” was noted. I returned this bill, saying I would pay when I received one stating my patient reference number. In Britain I have said, on occasion, “Excuse me, I’m not a customer; I’m a passenger (user, etc.). Perhaps I sound like an awkward so-and-so. Perhaps I am.

This "third station" business is fraught with pitfalls. Suppose the train starts at Ramsgate and stops at Broadstairs, Margate, Herne Bay, Faversham, and stations beyond. If somebody told me to get off at the third stop, then that would have to mean Herne Bay. But if they said "third station", the logical interpretation would be Margate, because the first station is Ramsgate itself. However, I would still take them to mean Herne Bay, trusting them to be illogical.
Similarly, if they told me to get off after the third station, I would take them to mean Herne Bay, not because the third station is Ramsgate and Herne Bay is after it, but because that is realistically then only station that they could mean.
I've always thought passenger==>customer was intended as an upgrade, to indicate that ticket-buyers were going to be treated with the same respect they'd get at Marshall Field, not as fare-paying cattle.
As to guest, it's routinely used by hotels, even though they always expect those who stay in their rooms to pay for the privilege.

Somtimes there are places to get on and off trains which are just a platform in the middle of nowhere, sometimes called a "halt" but without the ticket office, shops, left luggage, toilets etc you'd expect at a station.
To me "Get off after the third station" could imply you are to count the full stations and the next halt after the third is the one you want.