The plan you are talking about is ULIP, which has an inforce locking of 3 years. Though the policy is for 20 years but after three years, you can withdraw your amount at NAV price. You will be entitled to receive approx. 98% of your fund value. I'll personally suggest you not to close it now as you will only receive approx. 25% (Rs. 12500) against your saving of Rs 50000 as a surrender value. I am also a financial and tax planner and also associated with ICICI Prudential as an advisor. I am not sure but it seems that SBI Insurance advisor has misguided you but you don't worry as ULIP plans are not bad choice from investement and tax saving point of view. I am not sure about SBI but if we talk about returns given by ICICI Prudential then I can say that for last 5 consicutive years it is 37% while in other conventional saving schemes like PPF, NSC, KVP , bank FDs, we get max. 8-9% along with longer locking period as compared to ULIP.
If you have any other query, please feel free to ask.