Hey all. I need someone to quickly check my letter and correct if there are any major mistakes in it. Note that English is not my native language. Thank you.

(left out the salutation)

My name is Hans Verstegen and I work at the finance department of Martin&Co, which makes computer parts. I want to inform you about the following things.

My colleagues and I use our computers on a daily basis. Our company was looking for new computers, because the old ones are outdated. This is why we contacted HP. We contacted Mr. Rolando and ordered 4 computers for our business.
Unfortunately there were a few things that went wrong. This all happened one month ago. The models we received were wrong. I contacted Mr. Rolando and he informed me that the order was lost. I sent the order conformation again, so that your company could send us the right products. Only this took longer than agreed.

The right models were delivered yesterday. But this time we only received two of the four computers we had ordered. Unfortunately, we were too often disappointed by the services of HP. I know your company normally does not give discounts for delays, but in this case there are two incorrect deliveries. Does your company give discounts under these conditions? I think I am entitled to compensation. What do you think about a 15% discount on the entire bill?

I hope you can fulfil our request and we look forward to hearing from you.

Quick question: Should I use the linking words Firstly, Secondly and Finally(lastly) in the begin of every paragraph?