PBS Tier 2 Dependant extension

[S_E]

I have an indefinite leave to remain granted 15/08/2016. based on Tier 2 Shortage visa. My wife's visa is PBS Tier 2 Dependant which will expire 08/07/2017. We are planning to extend it, but when I am trying to IHS it ask me about expiry date of main applicant visa which is definitely confusing as my old Tier 2 visa is not valid now and was due to expire 08/07/2017 and when I tried to put the validity date of the ILR which is 20124 it calculate the IHS for 8 years, we only need to extend it to three years how can we sort out this problem

[S_E]

Sorry Some typing errors

I have an indefinite leave to remain granted 15/08/2016. based on Tier 2 Shortage visa. My wife's visa is PBS Tier 2 Dependant which will expire 08/07/2017. We are planning to extend it, but when I am trying to pay the IHS it ask me about expiry date of main applicant visa which is definitely confusing as my old Tier 2 visa is not valid now and was due to expire 08/07/2017 and when I tried to put the validity date of the ILR which is 2014 it calculate the IHS for 8 years, we only need to extend it to three years how can we sort out this problem

[S_E]

Another question please, my wife has been with me in the UK for 5 years and 7 months as a PBS tier 2 dependant so she qualify from the qualifying period for settlement but unfortunately DOESN'T meet the other requirements for settlement, Can she continue extending her visa as PBS and for how long (What is the maximum) and what is the realist time she can apply before visa expire.

Thanks