Cellphone contract

Another day another cellphone contract...Mrpmobile offered me a cellphone contract which ends on the 31st of July 2020. After my recent debacle with Telkom I decided to email them my intent to cancel my contract when the stipulated period comes....and that is when I was sent a response articulating that I will be held liable for payments to them in August when my contract has ended. I called them and asked why they cannot Bill me what I owe them since I have the intention of procuring a new contract with a new and trusted cellphone provider. I did not get a satisfactory response. Mrpmobile does not allow you to purchase cellphone data when it shuts you but they randomly send you data specials that suits their business model. At the end of the month you end up paying more than you can afford. When you do not have airtime during lockdown you cannot purchase airtime with money you have in the bank. You have to go out during the dead of night and buy an airtime voucher. I do not know why I took a contract with them.