我觉得句子里到圭亚那的货应该是你们运的,他们是收货人.照这样理解,我的翻译是：
Many thanks for your trust on our company and me （西方人习惯把自己放在后面的） as well.We shipped the cargo to Guyana a few days ago.The ETA is around October 25.
In favor of our further partnership,I would like to introduce our company briefly.I believe your trust and our capability will bring us mutual benefits （我加的,利益当然也很重要） and success.
Looking forward to working with you soon again.
这样分一下段落比较清楚些.