error on visas?? or... pliz help

i was issued with a dependant visa on 10 july 2008 with my 3 year old daughter as well.. we entered uk on 24july 2008. the visa was 2 years but apparently it expires on 15th on november 2010 instead of july
now i want to apply again i dont know whether
1. when i shpuld i apply .. july or november.
2. the home office insists there was an error as i should have been given 24 or 27 months not 28
3. am i elligible for indefinate leave to remain, my husband has been here for 4 years and has indefinate leave