Wont give my money back!!!!!

My contract is about to expire with Jabba Connect within 2 months,My Cousin took over the contract and settled the account and payed an additional R40 which was also their mistake of debiting to early in December. After settling the account, they then tell me that I have fore-fitted the airtime, If they would have told me this was going to happen I never would have settled the amount. I feel this is not legal, I did not force them to accept my money, nor did they force me to settle the account. I feel that settling an account early should be considered a good thing, instead they punish you for it!!! I Feel mislead!! I want my airtime or my money back. This is ridiculous.