Dawn - your payments can increase due to increases in income. It is allowable to reduce payments to the original amount agreed, and sometimes up to 15% off the agreed amount (although this may lengthen the IVA).
If there is a huge change to income it is still possible to get a reduction, but this involves going back to creditors to agree a variation to your agreed dividend.
Are you saying your IP has now included the shift allowance in your normal income? If so, I am not sure this is correct unless it's a definite increase each month. One of the experts will be able to advise later.
I still don't understand why the shift allowance is now being included. Ask your IP to explain why they are changing the basis of the calculation of your disposable income.
