Taking only the information you have given, it seems the solicitor may well have acted incorrectly:--
1. Not applying for legal aid when he presumably knew it was likely to be granted (otherwise, why would he have said he was going to do so?)
2. Not issuing any engagement letter with an indication of fee basis and the likely cost.
3. Engaging a barrister without client authorisation.
4. Demanding money without issuing an account.
Write a formal letter to the Complaints partner of the firm, & if the case is not resolved to your satisfaction go to the Law Society complaints procedure.
Note that what another poster says about legal aid having to be paid back may be correct, but if a solicitor is doing work on legal aid his hourly rate is often a lot less than for his other work so the amount the client would have to pay would be less than if legal aid is not obtained.
Note also that I hope none of this detracts from what Barmaid has posted. As a barrister, she clearly knows what she is talking about & the questions she has raised need to be looked into.