Dont ever accept upgrades from private banking

Received a call from private banking offering me an upgrade on my credit card. After asking a few questions I accepted, one of the questions asked was if I would be able to transact with my current card until I receive new card and this was confirmed on a recorded call. A few hours later I was unable to use my card or access any funds. Contacted fnb and they said it will take a further 24 hours, so I asked them to just cancel it as it had been a huge inconvenience thus far. Now I have to go through a whole process of printing and signing documents just to go back to what worked when so called upgrading just took a few minutes over the phone. This is really poor service from fnb and I would never recommend them to anyone and advise people to rather work with banks who know what they are doing.