The failed orders you have had previously, were they ‘on line’ orders where you entered the address yourself or via phone calls to the sales channel of whatever ISP you used , obviously if self selected, then provided you are using the correct postcode it’s difficult to see how it can go wrong , if you spoke to a customer service representative they could mistakenly pick the wrong address , if there are 2 addresses that are identical apart from the postcode, I suspect this is probably the issue.
TBH , you probably need to check that you are definitely using the correct postcode ( especially if you ordered service on line so it’s you selecting the address) ,
If your address is served by a telegraph pole , it ought to be easy to check the DP number on it , as it’s normally displayed on the pole , unfortunately without speaking to someone within Openreach after the order is raised , I don’t know how you could check that the correct PCP ( cabinet ) and DP have been allocated before another installation visit, the DP number will not be the same at this similar address .
If the wrong address has been selected, the same issue will present itself again , if you speak to a BT Customer representative, it’s possible they may have the option to send the order for a manual routing , perhaps you could call and hopefully get a representative that can do this ,
The first time was online, subsequent orders have been done by representatives. It's definitely the right address and postcode as they email you with the confirmation and the correct address and post code each time. None of it makes any sense.
Just noticed it’s 2 different exchanges , hence there will be 2 different exchange codes ( when using BT ) , Farningham numbers begin 01322-86, Dartford begin 01322-3 , you may not be ordering a phone service with your broadband, but if you did , and it wasn’t in the range 01322-86 then you would know it’s incorrect ( provided that your address is proper to Farningham exchange )
Use your immediate neighbour’s addresses in the DSL checker to confirm they return the same information as your address