I know you can get vehicle data from the HAYNES web site but you have to pay for specific vehicles or do you know any local garages that will help with diagrams from AUTODATA.
I struggle myself getting wiring diagrams...

 

Don't think haynes has done a manual for the Meriva B,

Back at the turn of the century when i have my iveco basd camper, i bought a copy of workshop manual from the main dealers, it was just over £100.. but was a 6 inch thick ring bound book thing,

i can imagine vauxhall would just laugh at me if i asked to buy a copy of the manual, then say it's only available in computer form, tho they might allow me to log on to read it at 50 quid an hour or something if i jump through the right hoops

 

Cant imagine any dealer letting you do that...If you have the time search ebay for a manual...They list manuals for meriva 2003-2010

 

sorry, i was joking about the dealer allowing access... they charge for everything by the hour nowadays,

so i could imagine them charging 50 quid to look at the wiring diagram on one of their computers.. but no print outs or copies to be made... when you get home and forget one of the wires colours/pin locations, you go back and pay another 50 quid for another look.