I am writing in response to your advertisement in …
I am writing to express my interest in…
I would like to apply for …
Thank you for considering my application. I am looking forward to meeting you in the near future.
Your prompt response will be much appreciated.
I should be pleased to attend for an interview at your convenience, when I could give you further details concerning myself.
I feel something should be done about…
I am writing to inform you that I find…unsatisfactory…
I would be very grateful if you could look into the matter as soon as possible. And I am looking forward to an early reply.
I believe you will take my complaints seriously, I would ask you to give back my money, or I would file my complaint to the authorities concerned.