Sevenoaks Rail Travellers Association

I have recently been buying some Advance Purchase tickets for travel in February. Interestingly, travel from Bat & Ball via Sevenoaks to my required destinations has not been offered, although it has been available via Blackfriars. For example:

• a journey to and from Norwich, with first class travel between Liverpool Street and Norwich in both directions via Blackfriars at £35.60 is cheaper than a standard class return ticket via Sevenoaks £42.25!
• a return standard class journey from Bat & Ball to Derby, via Blackfriars is £31.70, whereas the same journey via Sevenoaks is £82.70.

In both examples, arrival times at the destination, and departure times from the destination are the same!. Similarly, journeys commencing at Sevenoaks with the same arrival times at the destination, and departure times from the destination are not offering Advance Purchase ticket fares, even via Bat & Ball.

Are Southeastern trying to direct people away from their services if they want to travel on cheap Advance Purchase tickets?

I am experiencing frequent incidents of railway tickets that I have purchased not opening ticket barriers at Southeastern and Thameslink London stations: London Bridge, Cannon Street, Charing Cross, Blackfriars and St Pancras International are the main offenders. Is anybody else having this problem or know the reason for it?