Florida has 811, call before you dig. (Possibly other states as well.) It is a help but they hire subcontractors who may or may not do a good job. The sub takes photos of the paint marks and flagging to document what they found. If you dig and hit something they didn't find, I would think it isn't your problem, they screwed up.
I did have a similar problem with a cable company a few years ago. I wanted (or more accurately, Dear Bride wanted) cable tv, the company insisted they didn't serve our neighborhood. They were even nasty about it, too. I said that I was going to take a ladder and a pair of cable cutters and cut that d*mn cable and then we'd see who owns it. An hour later they called and said, yes, it is ours. We decided we didn't want to be their customer and went with dish (another circus, just with different monkeys).
Another issue with the same cable company . . . one of their in-line cable amplifiers slid off their truck and landed at my feet - yes, really! I picked it up and phoned them the next day, hey I have one of your devices, do you want it?
Technician STORMED into my office (in a bank building) and DEMANDED the IMMEDIATE RETURN of THEIR PROPERTY!!!! (Some thank you.) I said I'd bring it tomorrow, it isn't in my office.
That evening I opened it up and adjusted every tuned circuit I could find, distorted every wire-wound choke, and generally made sure that while the thing still worked, it would NEVER again work properly, and would drive them nuts troubleshooting it until they threw it away and replaced it.
Next day, I gave it back to them, here you go (and go bleep yourselves), have a nice day.
Best Regards,
Mike/Florida