請問有冇專幫人改cover letter/ resume 的公司 or 專人? (執英文為主)

You can send to my e-mail. No charge. Just help.

Yes. But it is very costly if you use a company to do it for you. I suggest you could ask your friend to do it for you. Or, to save cost and to get an immediate result, you could use the grammar and spell check features in Word. All errors in grammar will be highlighted and all speeling mistakes will also be shown with a list of correct words for your selection. Do and correct these errors until the markers have gone. Personally speaking, I find it very useful indeed.