What you want, and what you might get are two different matters.
There should be a process for an administrative appeal or review of the initial decision. If not, you do have the option of taking it for a review by the court. However, if you lose at court, you could have to pay additional fees (usually about $50 I understand). Whether either of these appeals can be done by some written declaration, I cannot say.
Here is the section:
22500. No person shall stop, park, or leave standing any vehicle
whether attended or unattended, except when necessary to avoid
conflict with other traffic or in compliance with the directions of a
peace officer or official traffic control device, in any of the
(a) Within an intersection, except adjacent to curbs as may be
permitted by local ordinance.
Note that the section does not indicate that the vehicle must be blocking pedestrian access, only that it be within the intersection.
And here is the definition of an intersection:
365. An "intersection" is the area embraced within the prolongation
of the lateral curb lines, or, if none, then the lateral boundary
lines of the roadways, of two highways which join one another at
approximately right angles or the area within which vehicles
traveling upon different highways joining at any other angle may come
To prevail, you are going to have to show the entire area and demonstrate that this is NOT an intersection as defined in the CVC. Your photo seems to indicate that you are parked within the area bounded by the prolongations and as such, would be within the intersection. Given the image you provided, I am not surprised that they upheld the citation.