Ledger Support can't/won't help me and insist that this address did not come from my wallet or 24 word seed.
How would they know? Does Ledger not allow the creation of Segwit compatible addresses (starting with a 3)?
Yes they do, and the BTC Segwit address my Ledger issued me starts with 36ez............
I notice on the blockchain that there is an exact same address relating to BCH - not sure why this is?
That's normal: BCH uses the same addresses. The address isn't funded on the BCH-chain, so just ignore it.
Ok
Anyone got any idea how I can access/retrieve my coins?
Have you tried
IanColeman? If you try this, do it offline from a Live Linux DVD (running from RAM). Don't risk compromising your 24 words by touching an online device.
What would this achieve if Ledger Support insist that my address did not come from either my 24 words or xpub?
This transaction was done with the old chrome apps
Did you verify address 36ezRREzDYH3uSvADoSSpoLZrFVigQkmLp on the Ledger's own screen before sending the transaction?
You didn't get given the option to verify the address back then with the chrome apps.