I would stick with him and ask his reccomendation for a new one.
Surely, he'll have some contacts for you.
As for whether a teacher is a good idea or not, i would say it is. Definitely. If you want to improve quicker.
There are some great lessons online. Scotts are good. Marlowes videos are great.
But the one thing they cant do, is correct you.
Correct your positioning, or form or technique or anything really.
You may be trying to learn a piece, and get stuck at a point and not know why.
If your with a teacher, they can point out where your going wrong.
And any questions you may have can be answered.
Feedback. Its essential to progression IMO (not the bad type of feedback )