Contact KRPC using e-mail - firstname.lastname@example.org .
By phone - call John on 07803 828 220. This is an T-Mobile phone that is used specifically for KRPC contact. Barring the battery going flat the phone is switched on all the time so even if you don't leave a message the phone will have your number, unless you withhold your number that is.
Phone calls and e-mail normally get a reply in a day or two at most.