loans and investments-reducing balance loans Q help!

[physics]

Andrew's reducing balance loan of $52000 over 15 years attracts interest at 11.75% p.a fortnightly. Repayments of$283.92 per fortnightly are made. During the loan the interest rate is increased to 12.5%p.a. fortnightly. fortnightly repayments r the same.
find:
1.the amount outstanding when the rate changes (i dont know when the rate changes.=.=)
2.the actual term of the loan

i know that
N= 15*26=390
I= 11.75 and then 12.5
PV: 52000
Pmt:-283.92
FV:?
Ppy/Cpy:26

then i get FV=$1.46 when the rate is 11.75 and wwhen I=12.5% FV: 13254.86
i'm lost... plz help.

[mba]

Don't you need to know when the rate changes to do the calculations? :I