AZ, Costumeczar, and Brandibaked are the only ones making sense here. Clearly this is not what the client ordered. It is the job of the decorator to know what he/she can do in a reasonable time frame with the equipment at hand and to decline or offer slternate suggestions if they can not produce what is desired. The OP did a reasonable job on a cake that should have been priced mush higher than $45.00, but it wasn't what the client ordered, so while it should have cost more than it did if that was what was ordered, the client was not wrong to say she didn't want to pay for what was clearly not the cake she had expected. The way she did it was not optimal, but she was actually correct.
While posters on CC tend to side with a decorator over a client, people in business need to know their limits and be able to communicate those to the client. Every potential inquiry is not one that has to be accepted. Learning that is a key to success.