dual sim is networked lock for 12 months retailer not telling customers the proper info

i bought a Itel A48 from this store .When i wanted a refund i was informed the refund is not possible as i was pass the 7 days. The device was advertised as a dual sim phone using vodacom as the primary sim.i wanted to use my current sim which is telkom in the dual sim but was informed from the vodacom call center that i must used the device for 12 months then only the dual sim can be unlocked.so i had to buy another device that i can used with my telkom sim