You cannot go to a company where you got an offer. Write a letter to the HR supervisor to

Dear Sir or Madam, I am writing this letter to convey my gratitude for considering me for the position of Assistant Manager at your company. Unfortunately, I have decided to continue my work with my present employer and hence cannot accept your offer. During my interview, I was impressed by the interviewers and their friendly yet professional attitude. Not to mention, your company offers a great working environment and prioritises employee growth. I have a friend who works in your company highly speaks of your management and office environment. However, the remuneration package that was suggested in the final offer letter is way less than my current salary. My employer offers several other benefits besides the salary and I see a great career growth here. I am thankful to you for the opportunity you have offered me. However, considering my job satisfaction with the current employer and the reward package, I find no other way but to decline your offer. I wish every success of your company. Yours Faithfully, Jayesh Bhuva