Hi Melanie,
Thanks so much for responding so quickly! I must clear this up to avoid any further confusion; I was actually posting on behalf of a friend of mine who didn't want to be named or be mentioned. To be honest, they are finding talking about any of it very difficult!!

Sorry for misleading you..
Anyway, I have found out some more details regarding the IVA and the letter my friend has received.
At the beginning, the IVA total stood at just over £10,000. It was the total debt outstanding plus the IPs fees for arranging the IVA. There was an additional £3000 to be paid to "complete" the IVA as the applicant was a homeowner.
Early on in the term of the IVA, the applicant missed 3 months' worth of payments. A letter was sent to the IP, asking if the IVA term could be extended for 3 months to make up for this. The Ip negotiated with creditors, and it was agreed.
Unfortunately, this happened again, early on in the term...and again the creditors agreed to the IVA being extended for a further 3 months. Since these "mishaps", all payments have been made in full and on time.
In October 2005, the applicant had sufficient funds to clear the remainder of the IVA (£5000) - the applicant wrote to the IP enquiring if it was possible to settle the IVA immediately to prevent any further payments, this was declined by the creditors.
The letter that my friend has just received has advised her that in order to close or settle her IVA, she must find the £3000 she agreed at the beginning of the term by March..
Furthermore, the IP is stating that their involvement and work throughout the term of this IVA has accrued costs in excess of £10,000, which the applicant must arrange to settle following the IVA closure..
The IP have have kindly offered the opportunity to pay these over 50 monthly instlaments once the IVA has been settled.