[senco-forum] query

WARNING!
Slightly rambling hastily written email!

A hypothetical situation

SEN funding (100% of it derived via Audit) all spent up! Some heated
discussion between SENCo and Head about what it 'should' be spent on and
what it is spent on.
Yr 9 Student - BESD Statement quantifying 15hrs TA support. SEN dept can
only provide 2.5! (If we re-direct support, it would leave a 'support
class' with 3 statemented students without any support).  BESD student
very much at risk of permanent exclusion.
SENCo highlights dilemma to Head. Also points out high likelihood of any
exclusion being overturned because of the school failing to meet his
Special Ed Needs. 
Head moans..."I can't magic money from no-where...." 
SENCo replies "fine - just to alert you and 'pass the buck'; I can only
work with the resources I'm given."
Head replies "we share the buck - we are jointly responsible"
Heads suggestion was to move BESD student (average ability) into support
groups to access support. SENCo declined suggestion!

Questions
1. Is there anything stronger than 'should' in any guidance about where
SENCos / admin support is funded from?
2. Any ideas on how to support this young man - to make his life chances
a bit more positive and to avoid perm. excl.?
3. Anyone found any effective ways to squeeze money and put it back
where it belongs?
4. Am I legally / professionally responsible for the failure to meet
this students needs?

Any equally rambling advice appreciated!
Thanks
Jess