We see quite a lot of cases like yours where the OP drives right from a side street into a YBJ and then stops in it. There is an exemption on YBJs for turning right, but adjudicators are ambivalent as to whether this applies in situations like yours. What you can do is submit representations stating that you entered the box to turn right in accordance with the exemption for turning right in a YBJ. See what they come back with.
There is the usual error we see in the PCN concerning periods for payment and for submitting representations. The LLA & TfL Act 2003 is flawed in that it gives longer to make reps than the payment period. Some councils state the correct requirements as per the Act, but this PCN doesn't. Read the section below "Do not ignore this notice" and ask yourself by when must you pay, (it you decide to do so). Pay particular attention to the penultimate sentence and compare it to the first sentence. Date of service is assumed as two days later than date of notice.