Dispute with architect - should I use solicitor or use RIBA?

[Sadsiblingatsea]

I have a dispute with my architect and wondered if I should use a solicitor to resolve it (I've had a consultation and they believe I have a case) or use the RIBA (Royal Institute of British Architects) dispute resolution service (which is much cheaper).
Potentially serious allegations of being charged for work not done and many hours of work which cannot be accounted for as well as other matters going against RIBA code of conduct.

I'd suggest looking at the RIBA complaints process and find out what the scope or limitations of that would be. What powers of enforcement do they have etc.