You'd be better going to RS. Have a look at
this page.
Suitable components would be Part Numbers 226-7277 (15uF @ 450v), 267-7321 (22uF @ 450v) and 324-5436A (33uF @ 450v).
Note that voltage, which is the DC rating and these examples are 85deg axial efforts.
You've been told correctly that you need to get the nearest value to the old capacitors. Cricklewood don't seem to stock anything suitable to replace the original 33uF job with, or the 16uF for that matter (nearest appear to be 47uF and 22uF respectively) although I've looked only at the page you've given the link to. You don't really want to start messing about wiring capacitors in series or parallel to get near to the value you want.