easy to get hard to get rid of

When shopping in Argos I got asked by a member of staff if I would like an Argos card.so I said yes I bought a few items then the hard sales started by phone would you like payment protection emails text with your balance which I said no to then was told why would you not want it.I was at work so said yes then £6.00 was added to my bill.so I decided to pay the bill off in full and cancel the account so I phoned card services eventually got through paid the full amount then told I would receive a further bill with interest on .better cards on the market.