My dog has had a few repeat bouts of ear infection
. Recently and the latest one has lots of pus oozing out.
Is it worth asking the vet to take a look under a GA to clean it out thoroughly?

All too often true ear infections (assuming it's not ear mites?) can empty a Bank account with all the 'try this, try that' that can happen.   Ask your vet to do a swab, culture and identification so the correct antibiotic is prescribed.

It may be your dog will eventually need an aural resection which although it involved surgery, may help sort out what's going on.

We have been dealing with this for .ost of brookes life. It was due to allergies found after referral to dermatologist. 
She has immunotherapy and topical treatments
She has had a ga a couple of times to clear the ear but we have avoided a full resection thank goodness
Even that doesn't always solve it especially if due to allergies.
Yes its been an expensive road but she us comfortable and last week for.the first time in years cytology showed nothing in the ears
Ime it does need a specialist to deal with. The pus would really concern me

If the dog is amenable when conscious (but often ear infections are very painful and this won't be tolerated by even the gentlest dog) then a good look down the ears is called for. The vet needs to send swabs to a lab to determine what the problem is and what the bugs are resistant to and then give the ears a good flush so that treatment starts with clean ear canals.

Just thought I would post an update . Vet admitted him today to have his ear completely flushed out, he had some Neptra ear solution into his ear holes and he has a 7 days course of antibiotics- cadaxxa which I have never heard of before so I hope it’s good stuff. The bill came to £227 inc vat