Thanks for the warning and well done on getting your money back and walking.
It shows the benefit of having the WG's profile open on your phone.
Maybe I'm missing something but in my experience not all girls will do OWO regardless of money and they all don't state this on their profile. If she said she only would do covered oral would that get a negative?
You are missing something but not sure how.

Of course, a WG would not deserve a negative purely on the basis of truthful advertisement ie didn't claim to do OWO or, at worst, put the sum clearly at the top of her profile.
However, that wasn't the case here. She ticked what is a fairly standard service on her profile to attract punters, deliberately and deviously (IMO) didn't put it was extra on there and the OP turned up on that basis - only to be told it was £30 extra ie £90 for a fairly standard quickie!
It's like a car dealer advertising a vehicle has something fairly standard like electric windows then when you turn up, they try to charge you £3,000 extra.
Of course, a lot of WGs do this but it doesn't make it right; in fact, it's bang out of order.

Thankfully, while it's common, it's but by no means the norm and as punters we shouldn't accept it as so.