So this is the time for me to say bye to a iPhone 6. I'm wating to buy a iPhone XR and i saw one on gumtree for 10k. The problem I'm sitting with is the device is on contract and they do have papers. I'm just scared they don't pay their bill and the device gets blacklisted. Will it be possible to setup an agreement stating that if the seller does not make the payment each month and the device gets blacklisted that i can take lawful action.

