Hi teachers and other friends:

I wrote a letter to a hotel booking website. I was requested to pay "a 10% deposit to activate my booking. (Is the "a" in the sentence before necessary? Or could I say wish you "a" happy birthday) The price on their website is so low, that I am not sure it is true. My letter is bellow:

Subject: Regarding Deposit

Hi HelpDesker,

I'm considering to book a room in Beijing China. But I doubt the safety and reliability of your services. I'm afraid the local property may not allow me to live in at the cost stated on your website even if I have paid the deposit you request. Then, there would be no way for me to draw back my deposit.
Could you give me any guarentee that I can trust in?

Best wishes!

Could I say my last sentence in a more proper way?