My wife has a Vanquis card (unfortunately) and a couple of weeks ago, I noticed that the estimated interest for next month's bill was over £90 - despite the fact that the balance had never gone above £1000 and the monthly interest rate being 4.516%. The simplest of interest calculations would therefore be 1000 x (4.516 / 100) = £45.16 estimated interest. We contacted Vanquis immediately to raise this with them and they told us that the interest is calculated on the average daily balance. When I pointed out that the balance had never gone above £1000 they were puzzled and said they would look into it and call me back. They assured me it was probably just an issue with the website and that the actual interest would be charged correctly. Needless to say, we never received a call. When the statement was generated there was indeed over £90 interest applied to the account, which was made even worse by the fact that the minimum payment was £50. We phoned back tonight and again got some explanation about the average daily interest calculation and that they had calculated that to be over £2000 despite the account never going above £1000 (the limit is £1750). The operator explained that the average daily interest was high this month due to a large purchase the month before (of £800). Still not buying any of this I continued to explain that the balance had never gone above £1000. Again, the operator agreed this must be wrong. They are currently looking into again and I'm assured I will get a call tomorrow. If I don't receive a call or the explanation is not satisfactory what should I do? It feels like I should be going straight to the Ombudsman with this regardless of the outcome tomorrow as how many other people won't have picked this up. In theory, you could be making the minimum payment thinking you're (slowly) reducing the balance, when in fact it is increasing!! Advice appreciated. AceHarvey