I am confused because, it looks to me like UCSB offers accounting.
http://my.sa.ucsb.edu/catalog/Current/Documents/2014_Majors/LS/Econ/Econ-Accounting-BA-2014.pdf
SLO doesn’t take a lot of transfers. They accept only Fall applicants and you’d be a junior in the fall of 2016 - meaning 2-3 years. (Acct has a higher unit count now) post transfer to get your BS in 2019. The link show you CalPoly stats.
http://admissions.calpoly.edu/prospective/profile.html
Or, you could stay put, focus on the quantitative side of UCSBs Econ department - graduate in May 2017 - and get an MS in Accounting in the same time-frame.
I’d encourage you to stay put and find a path through UCSB. It is a very good school and delaying your graduation is very costly and unnecessary.