Oh for heavens sake, I'm an alarm engineer of 35+yrs, my insurance company requires a service contract with an 'approved' company, and not even the one I work for!
If you don't do what is required by your insurance company and there is a problem, that will be their 'out'.
An non-approved company, one man band type, 4 hr breakdown cover, not the ones I know of.
Don't forget to have it serviced and KEEP the paperwork, I know of one company? that does not issue paperwork, just says it's on the computer so we can prove we've done it! Yea right.