Loan term will be extended to recover the increase credit insurance premium

In 2019 I took out a Personal Loan with Capitec Bank. According to my signed contract the repayment period will be 36 months ending 25/12/2021. Tuesday the 30th of June 2020 I received an email from Capitec Bank saying that loan term will be extended to recover the increase credit insurance premium. In short they say that my terms will be extended. 1),How is this practice possible to increase a person's installments without consulting with the customer? 2) How can my signed Contract be changed without my consent? After mailing Capitec to get answers NOBODY even tried to contact me. On the 2nd of July 2020 I had to phoned again and I was then told I MUST pay this and it was due to my account being in arrears. That I found very strange as I've NEVER missed a payment. The person assisting me was not helpful at all.