We had the same problem with a new property we manage.
It took some persistence but we eventually got BDC to understand and delete the (older) duplicate. In our case the old duplicate had been dormant for many years and our new account application clashed with it.
Contact BDC via 'phone or Extranet messaging and explain the problem in full i.e. why is there a duplicate and the exact action you want taken.
You can also use a third party for taking credit card payments in advance e.g. TAB, who we are trialing at the moment.
Set up a pay in advance policy along with a cancellation policy that will work for you, in conjunction with the third party this will solve the problem.
Do not cancel it! If you do, not only will you be paying the commission but the relocation costs as well, this could prove to be very pricey.
Do you have any kind of pay-in-advance system running along with a no-refund policy of some sort? If yes, you will know the booking is genuine when you take payment and any free cancellation period has expired ;-)
If you have a policy of free cancellation at any time then you have a 50/50 chance of it being genuine. If you are nervous to have a large gap in your calendar that you may not be paid for, then you can contact BDC to see if they are willing to cancel the booking themselves on the basis of it being over 30 days collectively.
The listed UK numbers are on this page, if up to date?
telephone contact by country
United Kingdom - Bristol - +44 1173008470
United Kingdom - Edinburgh - +44 1312473575
United Kingdom - London - +442086128159
United Kingdom - Manchester - +44 1618173540
Does BDC not have a maximum of 30 day bookings on their site? Is this just an email notification or have you double checked it's showing in Extranet?
Do you have monthly rate activated. Is monthly rate even working yet?....
Sorry, more questions than answers...
Check your Extranet calendar settings, you have missing information there e.g. allotment, prices, room open to book, minimum stay etc.
Check your own settings in Extranet calendar and be sure you do not have auto-top-up running.
You need to request BDC to add the CVC (rear code) to the booking requirement. Without it you cannot implement any kind of payment policy that covers prepaymnet, cancellation or no shows.
For your current no show the best BDC can do is request the booker to send the details anew, which of course they won't so no payment this time unfortunately. Leave this one as no show and waive the payment, therefore BDC will not charge you the commission. If you have already marked it as no show & chargeable, you will now need to contact BDC to change it to payment waived.