How to mend Vaillant 828

my vaillant boiler is saying a code com on it ?

my boiler will no work?

Vailliant turbo max plus 824e?

Vaillant 828E - no hot water?

Problem with the pressure in combi boiler?

vaillant ecoTEC plus boiler fault code - how to fix?

How do I fix f22 error on my Vaillent Ecotec Plus boiler?

Valliant Eco tec 28?

Vaillant Thermocompact Fault?

Vaillant Ecotech Plus 831 F22 fault?

how to fix water pressure its down at bottom of grey part?

Why is heating on at night?

how do I rectify the fault as detailed below?

Hot water comes and goes!?

What does f.25 mean?

Valiant thermostat , BMU-Err ?

Vaillant F22 fault?

Vaillant eco plus 531 boiler?

Advice?

Vaillant ecotec 831 plus?

Vaillant igniting issue ( domestic ) not CH?

Vaillant condensing boiler ecoTEC plus?

Vaillant ecotec plus 630?

No hot water, intermittent when air temp drops?

Vaillant ecomax 828/2 e water pressure sensor?

Vaillant vcw gb242 eh central heating problem?

Boiler over pressure on the hot-water side?

can i replace my Potterton EP2 2 way programmer with a Center EHE0200361 RF?

Vaillant VCW-Sine18 T3WFH Lights but then goes off after 5 Min?

how do I vent the heat exchanger?