Bad customer service - Mondo/MTN SP

Bad service experienced with MTN contract upgrade in May 2025. Both MTN and Mondo are refusing to resolve the issue by sending me from one to the other. I have been charged for a contract I do not have and have been paying for this line since June 2025 with both parties refusing to cancel the contract and reimburse me the monies that is being debited from my account. MTN is adamant that Mondo must refund me the money that I have been charged and that they must cancel the contract and Mondo is saying that MTN needs to correct my billing as I only have 1 contract with them but I am paying for 2 lines.