You try to help them...

Cust: I haven't got a fitting but I know what size I had last time, It's a 32H. Do you have anything in that size?
EM: We have loads
Cust: My bra has stretched since then. what size is next from a H?
EM: That would be a HH
Cust: I think it's more girth than the cup. I think I'm more a 33 than a 34...
EM: Did you want a fitting? I have no one waiting at the moment
Cust: I think if I just pick some and try them on and then get someones input that will be fine, yes...
EM: Ok...
(Cust goes upstairs)

Later, the fitting room door opens and she's dressed and ready to leave, without having asked anyone for input...

EM: How did you get on?
Cust: No... I'll need to try some more on but it's a start
EM: Oh, ok