I wouldn't take the blame, however I would put my hands up to making the problem worse and if they hadn't swore would have bought a small tube of silicone from home base and repaired it myself. However if they where abusive, I don't return don't call, don't answer there calls, don't tell them I wont be back, don't take there money, don't take anything to do with them what so ever I just walk and that's that.
There is fortunately nicer people out there and these types are in a minority, so I definitely wouldn't worry about not having there business.
I broke a £30 plant pot a few months ago now, and it was first clean so the guy didn't know me. I knocked his door and put my hands up to it and apologised, he just said don't worry, these things happen. I have since given him free cleans to its value, and he is a very good customer of mine.
So for a poxy bit of silicone which is easily repaired, its is certainly not ok to start giving people verbal abuse about it. Nobody should be putting up with that.