Cath, yes, I believe bees do deter hummers from feeding, or at least wasps do. This summer saw many times a hummer stop to drink, then fly away as a wasp rose up.

And yes, they are definitely leaving. I have only one right now, there is no chasing at all. A week ago I had two, and before that had 8 or more. We are getting a low of 35F tonight, so I hope he leaves soon.

Hummers are very visible at feeders early in the morning and at dusk, topping up for the night and after it.

There was someone else (or was it you?) who had a big bee problem earlier this summer. You might want to check that post out for suggestions.

As the days get colder, I find they are too cold for the biggests bees, and on cold days only the littlest bees are active. So your problem will ameliorate as the days cool off.

My only suggestion would be to plant a bee heaven like agastache nearby to lure them away.

Are they honey bees or yellow jackets? We have problems with yellow jackets this time of year but during the spring we had a 'swarm' of bees for at least a week. They eventually left but we found if we put out a weaker mix of nectar the bees lost interest.
This time of year we use the bee guards to keep the yellow jackets out of the feeders. The guards also prevents the surprise of YJ's popping out of the tubes when the Hummers go to feed! :)
You might try adding 1-2 more feeders.........make a stronger nectar mix for the bees in one feeder and hang two extra feeders elsewhere in the yard, filled with a regular mix for the Hummers
We have Anna's Hummingbirds year round so we have no fewer than 6-8 feeders to tend to. Come this winter we'll probably have 30 hummers to feed.

Below is our favorite feeder, and in the winter we add the large sizes.

Here is a link that might be useful: Best feeder

The hummers are pretty cautious, but they seem to get used to having bees around. In my experience it does inhibit their feeding somewhat, but they seem to stay pretty determined:

What a great picture! Thanks for sharing, mbrowne.

If there so many bees outside then the humming birds are scared.