Travelling Cattle Class On South Central

With all the new trains supposedly running now, why are South Central not using some of the better quality coaches that have been freed up to run better trains to Eastbourne?

All we ever get these days seem to be the old, cold, cattle trucks, with a slam door by each block seats. The windows on these trains seem to have a self opening feature that lets in plenty of ice cold wind during the journey. The seating is 3 seats by 2, and was originally designed for metro style service, not long distance. As a result the seats are too narrow to fit people in properly, especially as people seem to be 'larger' these days.

Where have all the good trains gone?