Somewhere other than Vodafone? I.e. an ISP that knows what they are doing. It's almost as though they are using the address, not the phone number.
At a guess Unicom are re-selling a TalkTalk Business Wholesale service, so Vodafone are confused. That could explain why they aren't using the phone number, as neither would appear in the BT Wholesale database they may be looking at.
However - the implication is they are ordering twice! One for each line.
As a side issue, looking two or three of the results here
I'm surprised your Dad's business line is OK. Though the service from TTBW is generally good, so maybe no need to ever contact Unicom.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
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