Grrr that surly London lady

So I go up to the counter at the pool, smile, and go, like we always do, "2 adults, 1 baby, 1 toddler please" and it's that surly lady again and she goes "that'll be £8.40" without the corners of her mouth so much as twitching upwards, and I go "have the prices risen recently?" and in the style of a reluctant teenager she goes "no-oo", and I go "do I have to pay for the toddler" and the lady goes "well how old is she?" (and do I imagine it or do her eyes roll upwards at the same time?) and I go "just over 2" so the po-faced lady says in the deadest of dead voices "that'll be £7" so I pay and smile, gesture towards Jasmine and go "at what age do I start paying for her" and she goes "when she's 3" and I say thank you and what I'm really thinking is that unhelpful surly cow should have asked how old the toddler was first before just charging me for her and trying to rip me off grrrrrrrrrrrr.