Concerned client

Today i got an email from capitec that my term will be extended by 5 months/installments because of insurance premium increase.i want to know if they can do that?i mean i took the loan in january 2020 I dont understand how u guys can extend my loan term by 5 months,the day i took the loan my contract was for 72 months at a fixed rate,i need a more detailed reason or info as to why i must pay more for a loan for wich i signed a 72 month contract? A deal is a deal and a contract cannot be changed/adjusted afterwords,atleast i wasnt told that when i took the loan,its a legal agreement between myself and capitec. So i would love to hear from u guys as i need clarity as to how that is possible and i did not even agree to anything nor sign a document or new contract/agreement where i give consent/permission to extend my loan term Im thinking of moving to a new bank