Momentum sends a locksmith to assist with keys locked in my boot but then fail to tell me that they will have to damage my car seat in order for them to take out my keys

On Monday the 16/10/17 I locked my car keys in the boot, seeing that i have a cover with momentum which im paying for. I then decided instead of asking hubby to bring me my spare keys let me rather call for roadside assist. I called their emergency numbers and they assisted me and told me the locksmith (LS) will be thereto assist within an hour. I patiently waited at the office. After an hour the LS was there and he successfully opened my car. Now because the car keys were in the boot the LS had to open the seat at the back to pull some wire to open the boot. Boot opened but now the clip that holds my seat was broken and now my seat at the back is loose. When i asked the LS if my car seat is broken he answered yes most of them break! Just like that, not a care in the world. I called Momentum and reported this and they said they will investigate and get back to me. Now no one is coming back to me. My argument is that had i been told that there are possibilities that my seat would succumb to such damage i would have asked hubby to bring the spare keys because i wasn't stranded i was safe at the office. I would have waited the hour that i waited for the LS. Now Momentum questing to you WHO MUST BE LIABLE FOR THIS NEGLIGENT ACT??? is this how you treat your clients?? My car is fairly new and i refuse to have a broken seat not even broken by me!! Im upset at your service!!