Merging Two accounts

My installer has created a new account (without my authorization) and configured my new bticino system on it - while I have a my former account I used in my old house for netatmo. Now I've tried to change email address, but I can't since email address is already existing... So I'm wondering if there is a way to merge two accounts - or any suggestion is more than welcome. Do you know how to reach assistance asking for merging the two accounts?