I had to fix a Frankie tap recently - I called their spares line and told them the style of tap - the name is important I believe - they asked how old the tap was - I said four years (you get free cartridges under 5 years it seems).
A hot and a cold cartridge came within a few days - I shut off the hot & cold (this will be your biggest challenge) then I unscrewed each cartridge and fitted the new. They're "handed" hot and cold to get the tap leaver the correct way round.
https://www.youtube.com/watch?v=VyfL2wLqPbA
Good luck...
April 2015