Breach of purchase agreement and escrow instructions??

[Jacob King]

HI I signed a purchase agreement for a home in Eureka, CA at the end of September 2021 that clearly states in section D, (loans) " this loan shall be at a  fixed rate not to exceed 3.5% ". Now today I received an email from the lender informing me that the interest rate has gone up to 4.75%. No warning.   The contract states that close of escrow shall occur 45 days after acceptance.  This never occurred.  How long is this valid for ?  The contract is between myself and a brokerage firm. Any advice or insight is greatly appreciated