Pathetic service

I'm very disappointed with the service that I have received from MBD Credit Solutions. I called on the 29/06 /2018 asking for a settlement amount, the person whom I spoke to gave me the amount which I wrote it down and also confirmed it before hanging up. On Monday I called to confirm if they did receive the payment and was confirmed. I then requested a letter confirming that the account has been fully settled. The lady told me that I can only get it the next day she promised to follow up on the matter. Next day I called again and was promised that I'll get it before the end of the day. This morning I have a informed that there's still a balance owing, which comes as a surprise to me because I was told the amount to settle and I was hoping that I should be able to get the settlement letter by now.