I googled my local Post Office to check their opening hours. The right hand part of the results shows various useful details, as often happens witha google query. These included the long obsolete 0845 722 3344 PO Counters number.

Is there anything that can be done to stop this happening? Not as bad as the fraudulent premium rate call connection "services" but neither useful nor helpful.

https://www.theguardian.com/money/2017/feb/04/beware-call-connection-services-charge-09-numbers

You will find that Google is very open to suggestions of alternative telephone numbers to show in its information boxes.
There is a thorough explanation of how this works (with some wise comment at the end) in this item from BBC Radio 4 You and Yours.

The whole basis of Google searches, as with much of what we use as "knowledge", is that information is provided on the basis of availability, not authority.
Any suggestions about how to change this fundamental aspect of how we live these days?  ;)

Royal Mail group is to blame by using 084 numbers for everything for as long as they could get away with it and also to blame for not throughly checking that Google has now changed them all to the 03 equivalents.

I would email the senior managment of Royal Mail and The Post Office using the contacts listed at ceoemail.com to ask that they follow up with Google to ensure that all remain 084 prefixed numbers listed by Google are changed to 03 prefixed numbers.

However the bigger problem is with Ofcom since after five years it is clearly shown that this problem will only ever be cured if Ofcom sets a date for the cessation of all  084 and 087 prefixed number and demands that anyone who wants to charge for services by phone moves to 09 prefixed numbers controlled by PhonePay Plus.  And that includes people like ADT who's burglar alarms can all be reprogrammed or rechipped to dial 080 numbers instead of 0871 numbers............

And any of that work by ADT or other burglar alarm companies must be required to be done at their own and not the customer's expense.............