Is the wording in F detailed, specified and quantified in F? Or is it vague and woolly with wording such as “access to”, “would benefit from”, “regular”, “up to”, “or equivalent”, “opportunities for”, “as appropriate”, “would be useful/helpful”, “such as”, “e.g.”, “etc.”, “as required”, “as advised”, “key adult(s)”, “small group”? If it is the former, it can be enforced, including via JR if necessary. The LA is ultimately responsible for the provision in section F, so have you raised the non-provision with them? Unfortunately, if the wording is vague and woolly, it cannot be enforced and you should look to improve the wording, via appeal if necessary.
Why is DS on a reduced timetable? Is that something you want because DS can’t cope? If so, when did DS turn 5? If it was before September, is alternative provision in place to ensure DS still receives a suitable full-time education? Even if it was since September, the LA is still responsible for the provision in F if it is worded correctly. Or is the reduced timetable being imposed by the school despite you wanting DS to attend for longer? If so, are they formally suspending each time?