and very interested to learn that South Yorkshire Police have advised you not to pay a bill. I'm surprised because this is not normally something that the Police will ever do - they cannot possibly have any evidence to support your assertion that you are not liable for the amount being claimed - other than your own version of events.
A dispute over payment of a bill isn't a criminal matter, it's a civil one, and when someone goes to the police over such matters they would normally provide an incident reference number just for the record - they cannot and will not take any action whatsoever unless someone alleges that a criminal offence has occurred, and then only if their investigations confirm that there is sufficient evidence on which to proceed.
That's why I'm interested to learn that a Police officer has advised you not to pay a bill. Can you please categorically confirm that this is what has happened? Forgive me for probing like this, but it's very important, and could have a bearing on many other cases.
If MBS (or anyone else) wants to pursue someone for non-payment of a bill they must do so via the civil courts, the police wouldn't be involved at all, unless, as I previously mentioned, someone provides them with evidence of a crime. As far as I can see you haven't done that - you're simply disputing that you owe the money. If you don't pay, it's up to MBS to decide what to do.