4gig Evod promotional data a ****

I received a 4gig evod promotional data from mtn which expires on the 28 of february later on i then bought data which expires on the 4th of April but whenever i login on evod mtn use the data i bought later on and this is not the first time it happened i recharged my account then checked my balance and my airtime was short i called mtn and received a call tomorrow line as always