I've had a credit card with AvantCard (now AvantMoney) for quite a number of years. But having recently transferred my balance to a provider offering 0% interest for 15 months I then wrote to AvantCard to cancel my account/card with them, in compliance with the stated terms and conditions.
I then received a call from a customer services rep. wanting to speak to me about my letter. I refused to answer security questions as I didn't know this person from Adam so they asked if I would call back, which I attempted to do 3 times... and was kept on hold for so long each time I just had to hang up. Beware anyone needing to speak to someone in AvantMoney/AvantCard with a query, you have a better chance of winning the lottery!
I'm still no wiser as to whether or not my account has been closed as requested, time will tell. But from a customer service point of view I would recommend that you not touch them with a barge pole!