ISPs coming out and bothering you cause you pirate stuff? Never heard of it.
You must have the distinct privilege of not living in the USA or several other Western countries.
I’d jump ship immediately if I got one such letter.
If you mean jump ship off that ISP, there’s nothing you can do. You can go to another ISP (if there even is one in your area), who will do the exact same thing. You can jump ship entirely and not have internet, I guess.
DRM exists to "protect’ the software developer, i.e. protect profits by making sure every copy has been paid for and to force people to buy multiple copies in certain cases. DRM never has and never will be for your (the consumer’s) benefit.