Vodacom phoning you to change your plan

Please be aware that they are phoning you to tell you that your contract amount will be changing and that you need to change your plan (not upgrade/downgrade) and then they tell you, you can get better pricing because the pricing they offered you when you took out the contract is very high. they will continue phoning/harassing you until you answer. and then when you start saying but I agreed to a fix amount, minutes and data, I don't understand the reason for your call or try and get information out of them about your current plan then suddenly they are not aware that you have a fixed plan for a period.