Seat slider/adjuster components needed

Hi there, I've had problems with seat slider / adjuster mechanism under drivers seat of my 97R 1.4CL; it's all simple mechanics, but I need to replace 2 small spacers/clips made of white plastic which have worn badly and become mangled in the runners. There's one clipped round the back end of each sliding carriage, which moves back along the runner with the chair; the other problem is a small wedge-shaped piece of the same white plastic that locates the sliding bolt of the seat adjuster lever under front edge of seat. Without it the bolt is very difficult to align properly, and often won't click in when handle is released.

Sorry, wordy description of very simple items - does anyone know if these can be found as replacement parts? Must cost about pence per item if they are available! Seems pointless stripping them out of a scrapper as likely to be in similar state.