MTN harassment

I am sick and tired of MTN harassing me and the people on my MTN contract. I have a contract with MTN which I am happy with and I do not want to change or upgrade. For the Last 11 months MTN has been calling me and the people on my Contract harassing us and trying to force us to upgrade our package after multiple time of us all telling them we will not change our contract and that we are happy and we kept telling MTN to stop calling us for contract upgrades we are being called a minimum of 8 times every week since I got the contract and after trying to speak to MTN about the harassment I just keep being put to a different person and no one will take my call to get them to stop calling me but they can always call me when they want money the are willing to harass me 8 times a week minimum and I am sick of it. They need to Learn that NO means NO. I am fed up with MTN at the moment.