There are several possible repairs depending on how bad the seat is and in most cases we can avoid the horrendous expense of buying new seat foam and covers. It is sometimes possible to add more foam padding or hold the old foam together with a cotton cover. Where damage is minimal swapping the front seats foam over may extend the life considerably as they each wear on opposite sides.
We will be more than happy to advise you on the various possibilities and give you a quote if you wish at our workshop on a Saturday morning.