Hello. I will be grateful for some help with English tenses.

1) Are both variants possible: "she has been helping me for years" or "she has helped me for years"?
2)The same question: "they have tried to do it since March" or "they have been trying to do it since March"?
3)Please help me with a lexical question. Is it possible to say "to sharpen the situation" in the meaning of "to escalate the situation"?
Thank you very much for all your help.

All of your sentences in 1 and 2 are correct.

We wouldn't say to sharpen the situation, but escalate the situation is fine.