Nonsense.
For any extras above HJ you just subtract $50 from the price you would usually pay at a $75 shop. Girls know this.
Example $75 shop
HJ $50
BJ $100
FS $150
Example $130 shop
HJ included
BJ $50
FS $100
These are example prices, so if the girl charges $200 at the $75 shop, she will charge $150 at the $130 shop.