I think I was the one who replied to your original enquiry.
To improve our service, PTC has been working with Hornby to supply parts and track through our (PTC) online global e-store. The changeover has meant temporarily, the components C8523 and C8524 became unavailable in the UK. The lead time for supply from the manufactuer in China has meant the Scalextric parts packs will be available at the beginning of February.
Hornby and PTC sincerely apologise for any inconvenience this may have caused.