Lease extension - registration doc and deed of variation

Hello - I wonder if anyone can help me please. I have extended the lease on my flat and my solicitor confirmed nearly two months ago that he needs to send me the registration doc and deed of variation. Despite chasing him 4 times he still hasn't sent these documents to me and I am getting very anxious. Is there anyone that I can complain to about this. I don't think it's worth complaining to the solicitors firm as my solicitor is one of the owners/senior partners.

Thank you for all your help.