Verb conjugation of "curtail" in English

The billing of additional working hours is not justified, since it was our request to download the software and wait for the new version. They have admitted the error of the translation.
Everything in your letter is perfect! Almost no errors and the writing style, very impressive! After this first year in England, you have also improved your vocabulary and the grammar skills.
I want learn Spanish because of my girlfriend from Guatemala. She is from Latin America. And of course I want improve my grammar too. I like to hear it, but speaking is still hard. Hasta Luego.