Brake lines are easy, as long as you have the right tool, a flare nut wrench.
If you were having difficulty disconnecting the "soft" line from the hard line, then the hard line fitting could have been a little rusted onto the soft lines fitting. a little rust eater could have helped you with that.
Otherwise if they didn't couldn't get it off that way, they probabaly used a torch to heat up the fittings and then broke them loose.
For future reference:
take off brake line from caliper with socket or wrench, then take a flare nut wrench and open end wrench and disconnect the other sides fittings, repalce with new lines, use new crush washers on the caliper side of the line, and re-tighten everything.
Pretty easy actually, unless you had seized fittings.