During a job interview with the lead engineer of a big company in the UK, I negotiated a salary after he told me I am accepted for the job and asked me about my salary expectations. Three months later, when asking me about my expected start date to finalize the contract, the HR told me that she can only offer a salary that is £6k per year than the original agreed one. And then she told me to tell her if that works with me so she can send me the contract, I am really confused and shocked that such a highly regarded big company would do such a thing and I don’t know how to react, any tips?
"I am a fresh graduate so it’s literally my first job which is why I have no clue what to do, and no there was no there was no offer letter because I didn’t need it at the time."
Contact your new manager and ask for advice.
If you are lucky this is a lapse in communication within the company and can be put right via some polite conversations with the right people.
If you are unlucky then the higher offer no longer exists and you will have to judge whether you want to accept the lower offer. Since there is no record of your previous salary negotiation then you will be unable to force the company to pay you the higher rate.