I presume this now means that you don't have arrears?
Then its correct -
Let's say the redress is 30k and you have arrears of 18k, then the arrears are cleared first leaving a balance of 12k to be refunded.
For any additional cost that the arrears cost you, then the compensation amount should cover that and assuming the redress was in excess of the arrears and that if the correct interest rate was aplied you would not have gone into arrears, then you also need them to correct the record with the ICB.
So you need to work out ho much extra the arrears cost you and whether the compensation amount sufficiently covers that.