Thesis Advisor conundrum
You've not really commented on your thesis advisor's role as a research supervisor, which is quite different from being an instructor. Someone can excel in one role but be [almost] incompetent in the other. 

Consequently, it's hard to give you solid advice. The basic question is if your advisor's unavailability is impeding your research progress. If so, then you should definitely explore other options, if possible. For instance, look for a co-advisor for your project with A'. If no options with A' pan out, then you should consider switching advisors.

However, if the teaching style doesn't carry over into research issues, then it may be worth your while to wait and see if things improve.