How do I change my auto-entrepreneur APE code?

I am registered as an auto-entrepreneur and have been trying for months to get Assurance Responsibilite Civile Professionnelle. Two assurance companies that I have contacted just do not respond to my queries, but I have finally found one that does. They have looked at my auto-entrepreneur registration documents and tell me that, because I have been listed as Maconnerie this means that I am a builder. I have never said that I was a builder. I just do renovating and finishing works. I need to know if it is possible for me to change the code I am listed under. The assurance company tell me that, as a maconnerie, I cannot have a simple Assurance Responsibilite Civile Professionnelle, that I must have a decennale, which I understand is very expensive and, in my case, totally unnecessary because I will never be carrying out any building work.

I actually registered in person at my local Chambre de Metiers, paying the €79 fee, because I wanted to make sure the registration was done correctly, but it seems that the lady who dealt with my registration misunderstood.  I have already written to the Chambre de Metiers but, as they didn’t reply to my last query to them, I thought I’d ask you what you think?