Legal Question in Civil Litigation in California

Since you seem to know the basis legal principals and write intelligently, I think you can handle this own your own. Point out to her:

1. since she drew up the contract anything that is unclear is interpreted against her interests;

2. a reasonable person would assume that you were intending to go to a local gym and not on some distance away;

3. she has caused a major change in the contract by changing the site of performance so that is a reach by her and the contact can not be enforced beyond her being paid for what portion of the contract she has completed;

4. she probably knew a long time ago that the gym might close and must have known for a few months they definitely would close [how did they find so quickly a new place to house the gym?];

5. what she is now offering you for the future is much different then the easy of training that has existed so there is a breach as you are not substantially getting what you contracted for;

6. she has made the contract null and void and the burden is on her to prove that you owe her more money, but if she sues you will cross-complain that you were paying her more than otherwise because of the geographical closeness to your house and how you will have to spend the time finding a new trainer and starting over almost from scratch as a new trainer may feel what she was doing was not worthwhile;

7. her attitude makes it impossible to have the close relationship needed for a personal trainer so she has breached the contract in that fashion too.

You then have to see what she will do. Most likely she will back down as it is not worthwhile for her to do much over $600. You can not sue her at this point and you are not likely to be able to show any illegal behavior on her part.

Good luck.