Mbd attorneys settlement letter

I had an account with Jet which was handed over to MBD, whom I contacted to arrange settlement and I tried to pay by debit order or get their bank details, the consultant told me to pay at Jet which I went on the 30.11.19 but Jet was offline I couldn't pay so I came back the following day I settled the account to my surprise they told I forfeited the settlement offer bcs I paid a day later when I told them why I paid late they said it's their problem, I asked to speak to the consultant supervisor of which he dropped the phone on me and they don't respond to e-mails I'm sending them to request a paid up letter or don't call me back