We all seem to be making similar mistakes in dealing with Citi, this includes myself as I had a less than satisfactory encounter with them earlier in the year. Next time I try to deal with Citi, during the upcoming points season, I'll get everything in writing. Speak to them first, for sure, but then have them confirm what was said in writing. If nothing comes (no fax, no email) assume that what you heard was a crock and ring again.
With Citi, anything you can't prove is worthless and just ends up in a loop of he said, she said, I thought someone said.
Alternatively, as all large institutions record conversations these days, and let you know that up front, attach a recording device to your phone and before your converstion with the CSR begins let them know that for quality assurance purposes your phone call is being recorded (big smile).