How/When to "fire" external designer

mr-914, just got also another round of designs (4!!! and i am surprised by the number as to me shows that they are now going towards quantity in case I like something) that are all disappointing to me. Yes, on their portfolio I had seen and pointed design directions I liked but I feel that are not there in the designs they prepared.
Anyways, they have been payed all the project actually as, my stupid mistake, they tied together the website design in the quotation (which I agreed on and signed) so the down payment (that fully covers the logo design/development) has already been payed. Stupid, expensive, painful mistake. In any case though, another lesson learnt.