Are you sure it is bees and not badgers?
Sure it's not wasps, bees don't dig but iirc wasps have been known to exhibit that behaviour when nesting?
A quick goole suggests it might be wasps

Grenade.
They're a breed of bee's that have been able to withstand the onslaught of the deadly disease that has wiped out most of the bee's in the UK. And you're going to kill more of them![]()
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Japanese Hornet is watching you, and plotting against you!

Contact your local council Pest Control office. They'll provide advice and will probably deal with it (for a fee)