Have they given you a new date?
What stage are you at? The timescales are:
Stage 1 - they have 6 weeks from receipt of your first request for SA to tell you whether they will be going ahead with it.
Stage 2 - If they decide to go ahead with SA, they have 12 weeks to complete all the assessments, and decide whether to issue a statement or not.
Stage 3 - If they do decide to issue a statement, they have 8 weeks to issue the Final statement (this includes issuing the proposed statement to you, and gives you 15 days to get your comments back).
Sounds like you're at stage 2.
Write to head of SEN dept and remind them of their duty to keep within the timescales. The whole process must take no more than 26 weeks in total.
Not sure what else you can really do at this stage except make a note of the delay, it might be useful to include in future (eg if you go to tribunal, complain to LGO, or Judicial Review etc).
Sadly this probably won't be the first delay and display of incompetence you're likely to encounter 