Leaking Saunier Duval micro aculator problem.?

If it is from the microaculator not the pipes its new microaculator time. Boiler will have to come off wall to change it too. If I were you I would consider taking a Homeserve instant policy out with Group Service (Vaillant, Glowworm, Saunier Duval) as the boiler will then be insured for a year and they will send someone out to look and then two people out to do the job all inclusive in your one payment