Cough...
It's not easy to tell as it's all from your point of view.
However if you have done 20 hours and not gone solo what is the reason?
Is it because you can't manage landings properly? Is it that your radio is horrible?
You've done everything up to t/o and landings. Normally where I work we would proceed to the next lesson possible if the weather is not sufficient to practice t/o's and landings. In that case it could be advanced turns i.e. steep turns 45-60 deg's bank. Beyond this it would go toward Navigation if the practice of landings cannot be performed. There's a few more examples but you may get the idea.
One thing I should state, you can't let someone get away with charging one hour if you only do 45 minutes of briefing, this to me sounds like theft and does not give a good view of the FI in question.
My sincere opinion is that if you feel there is something wrong, talk to the chief above about it. If you can't handle doing that then talk to the customer service rep if there is one.
OR
If you speak directly to your F.I and he seems not to give a good and clear reason or you feel it's simply not enough- Swap instructors.
If I was in his shoes and didn't feel I could make you any better I'd definately suggest you go with someone else.
PLEASE remember it's YOUR MONEY!!!!