Vodacom contract

Good day one of the Vodacom consult called me, he said Vodacom is thanking me of being a loyal customer, in that point they gonna increase my 10G data contract to 20G with the same amount I'm paying,they not gonna increase anything,so I agreed to that only to find out that the guy is lying he need sales on his said okay, I received sms says I'm gonna pay more money, I called Vodacom the lady by the name of Pheliswa said there is nothing she gonna do,she will just escalate the matter as I was busy talking with her she kept quiet for 20 minutes I thought she was busy on the system, she can back and say is there anything I can do I hope I'm gonna get help