Re. my Thomson DT16300 box?

Why is my box not allowing me to " series" record tv programmes anymore as it is on a 14-day (+extendable) preference but only allows 8-day recording. Tried set-up, help,then pressed green,blue then green buttons which re-formats the disk and wipes everything clear but still does not correct the problem of allowing me to record a "series" of programmes (14-day instead of the 8-day option I only have .