the reason that you are returned to cvt rather than dropped at bournemouth (which is closer) is because the airline have a responsibility to get you to your destination, not halfway, so for the company it is easier for them to get you back to coventry and either refund your ticket or offer you an alternative. if they dumped you at boh then you would then need hotel, taxi, further transport via a 3rd party etc etc, unfortunately they are cutting costs rather than giving you satisfaction.