I have an update on the service light/spanner reset. I found a diagnostic tester online call OBDSTAR X-200 its an OBD reader, Service Light Reset and Electronic Handbrake diagnostic unit. They come from China and cost £179. The company stated it would reset the Maserati service Spanner and milage and if it didn't they would give me a full refund.
So I took the plunge and bought it, today it came and I tried it on my 2007 Quattroporte and it has reset the mileage to 12499 and days to 365 and the service Spanner in the dashboard no longer appears. Well worth the money it has paid for itself already as the only other option was an oil and filter change at an independent for £420.
The web site is
www.OBDStarTool.com hope it helps.